150 Amazing Science Words That Start With H

Published On: October 7, 2026

explore 150 science words that start with h

If you are looking for science words that start with H, this list is a simple way to build your science vocabulary. It includes useful terms from biology, chemistry, physics, astronomy, medicine, Earth science, and environmental science.

Some terms, such as hydrogen, helium, heat, and habitat, are common. Others, such as homeostasis, haplotype, and Hubble constant, are more specialized. Each word has a simple meaning and an easy example sentence to help students understand it.

The scientific terms below are based on standard scientific usage. Resources from NASA and the National Institutes of Health also use many of these terms in their science glossaries. (NASA Science)

Table of Contents

1. Biology Science Words That Start With H

Biology terms, their origins, meanings, and example sentences
Word	Origin	Meaning	Example Sentence
Habitat	Latin habitare	The natural place where an organism lives.	A forest is a habitat for many animals.
Habituation	Latin habitus	Becoming less responsive to something after repeated exposure.	The bird showed habituation to the nearby noise.
Haploid	Greek haploos	Having one set of chromosomes.	A human egg cell is haploid.
Haplotype	Greek haploos + typos	A group of genetic variations inherited together.	The scientists found a common haplotype.
Hapten	Greek haptein	A small molecule that can cause an immune response when attached to a larger molecule.	The hapten was attached to a protein.
Hematopoiesis	Greek haima + poiesis	The process of making blood cells.	Hematopoiesis takes place mainly in bone marrow.
Hemoglobin	Greek haima + globus	A protein in red blood cells that carries oxygen.	Hemoglobin helps carry oxygen around the body.
Hemolysis	Greek haima + lysis	The breaking down of red blood cells.	The test showed signs of hemolysis.
Hemostasis	Greek haima + stasis	The process that stops bleeding.	Platelets help with hemostasis.
Herbivore	Latin herba + vorare	An animal that eats plants.	A cow is a herbivore.
Heterotroph	Greek heteros + trophe	An organism that gets food from other organisms.	Humans are heterotrophs.
Homeostasis	Greek homoios + stasis	Keeping internal body conditions stable.	Sweating helps maintain homeostasis.
Homology	Greek homologia	Similarity caused by shared ancestry.	The bones show homology between the species.
Host	Latin hospes	An organism that supports another organism.	A mosquito can act as a host for a parasite.
Hypha	Greek hyphē	A thread-like part of a fungus.	The fungus grows through the soil using hyphae.

2. Chemistry Science Words That Start With H

Chemistry includes many important science words that start with H. Hydrogen, acids, chemical bonds, and reactions are common topics in chemistry.

Chemistry terms, their origins, meanings, and example sentences
Word	Origin	Meaning	Example Sentence
Hydrogen	Greek hydor + genes	The lightest chemical element.	Hydrogen is the first element on the periodic table.
Hydrogen bond	Hydrogen + bond	A weak attraction involving hydrogen and another atom.	Water molecules form hydrogen bonds.
Hydrogen peroxide	Hydrogen + peroxide	A compound with the formula H₂O₂.	Hydrogen peroxide contains oxygen and hydrogen.
Hydrocarbon	Greek hydor + carbon	A compound made only of hydrogen and carbon.	Methane is a simple hydrocarbon.
Hydrochloric acid	Hydrogen + chlorine + acid	A strong acid containing hydrogen and chlorine.	Hydrochloric acid is found in the stomach.
Hydrolysis	Greek hydor + lysis	A reaction that uses water to break a compound apart.	Water helps start the hydrolysis reaction.
Hydroxide	Greek hydor + oxys	A negatively charged ion containing oxygen and hydrogen.	Sodium hydroxide contains hydroxide ions.
Hydroxyl	Greek hydor + oxys	A chemical group containing oxygen and hydrogen.	Ethanol has a hydroxyl group.
Hydrate	Greek hydor	A compound that contains water molecules.	The salt formed a hydrate.
Hydride	Greek hydor	A compound containing hydrogen joined to another element.	Sodium hydride reacts with water.
Halogen	Greek halos + genes	An element in Group 17 of the periodic table.	Chlorine is a halogen.
Halide	Halogen + -ide	A compound containing a halogen ion.	Sodium chloride is a halide.
Hydrogenation	Hydrogen + -ation	Adding hydrogen to a chemical compound.	Hydrogenation can change the properties of an oil.
Hydration	Greek hydor	The process of combining with or adding water.	Hydration helps dissolve some substances.
Hydrazine	Greek hydor + azo	A chemical compound containing nitrogen and hydrogen.	Hydrazine has been used as rocket fuel.

3. Physics Science Words That Start With H

Physics uses science words that start with H to describe energy, particles, waves, motion, and forces.

Physics terms, their origins, meanings, and example sentences
Word	Origin	Meaning	Example Sentence
Hadron	Greek hadros	A particle made of quarks.	A proton is a hadron.
Half-life	Half + life	The time needed for half of a radioactive material to decay.	The isotope has a short half-life.
Hall effect	Named after Edwin Hall	A voltage produced across a conductor in a magnetic field.	The sensor uses the Hall effect.
Hamiltonian	Named after William Rowan Hamilton	A function used to describe the energy of a physical system.	The physicist calculated the Hamiltonian.
Harmonic	Greek harmonikos	Related to a regular repeating pattern or vibration.	The string produced a harmonic sound.
Harmonic motion	Greek harmonikos	Repeated motion around a central position.	A spring can show harmonic motion.
Harmonic oscillator	Harmonic + oscillator	A system that moves back and forth in a regular way.	A spring can act as a harmonic oscillator.
Heat	Old English haetu	Energy transferred because of a temperature difference.	Heat moved from the hot cup to the air.
Heat capacity	Heat + capacity	The amount of heat needed to raise a substance’s temperature.	Water has a high heat capacity.
Heisenberg uncertainty principle	Named after Werner Heisenberg	A rule about limits on measuring certain particle properties together.	The Heisenberg uncertainty principle is part of quantum physics.
Helicity	Greek helix	A property related to the direction of a particle’s spin and motion.	The particle’s helicity was measured.
Hertz	Named after Heinrich Hertz	The SI unit of frequency.	The radio signal has a frequency of 100 hertz.
Higgs boson	Named after Peter Higgs	A particle linked to the Higgs field.	Scientists found evidence of the Higgs boson.
Holography	Greek holos + graphein	A method for making three-dimensional images.	Holography can create 3D images.
Hydrodynamics	Greek hydor + dynamis	The study of fluids in motion.	Hydrodynamics helps explain water flow.

4. Astronomy Science Words That Start With H

Astronomy has many interesting science words that start with H. These terms help describe stars, planets, galaxies, and the universe.

Astronomy terms, their origins, meanings, and example sentences
Word	Origin	Meaning	Example Sentence
Habitable zone	Habitat + zone	The area around a star where liquid water may exist on a planet.	Earth is in the Sun’s habitable zone.
Hadean	Greek Hades	The earliest geological eon of Earth.	Earth formed during the Hadean eon.
Haumea	Named after a Hawaiian goddess	A dwarf planet in our Solar System.	Haumea has a very unusual shape.
Heliosphere	Greek helios + sphaira	The large region influenced by the solar wind.	The spacecraft traveled through the heliosphere.
Heliopause	Greek helios + pausis	The boundary between the heliosphere and interstellar space.	The spacecraft moved toward the heliopause.
Helioseismology	Greek helios + seismos + logos	The study of vibrations inside the Sun.	Helioseismology helps scientists study the Sun.
Hertzsprung-Russell diagram	Named after Hertzsprung and Russell	A graph used to compare stars by brightness and temperature.	The star was placed on a Hertzsprung-Russell diagram.
Hubble constant	Named after Edwin Hubble	A value that describes the expansion rate of the universe.	Astronomers measure the Hubble constant in different ways.
Hubble’s law	Named after Edwin Hubble	A relationship between galaxy distance and how fast it moves away.	Hubble’s law supports the idea of an expanding universe.
Hubble flow	Named after Edwin Hubble	The large-scale expansion of space.	Galaxies take part in the Hubble flow.
Hydrogen line	Hydrogen + line	A radio signal produced by hydrogen atoms.	Astronomers use the hydrogen line to study galaxies.
Hypernova	Hyper + nova	A very powerful type of stellar explosion.	A hypernova can release huge amounts of energy.
Hypergiant	Hyper + giant	An extremely large and bright star.	The hypergiant was observed in a distant galaxy.
Hot Jupiter	Hot + Jupiter	A large gas planet that orbits very close to its star.	The hot Jupiter has a very short year.
H II region	Hydrogen ionization notation	A region of space filled with ionized hydrogen.	The telescope photographed a bright H II region.

NASA describes hydrogen as the lightest element and defines the Hubble constant as a measure of the universe’s expansion rate. (NASA Science)

5. Medical Science Words That Start With H

Many science words that start with H are also used in medicine. They describe organs, cells, body processes, and health conditions.

Medical terms, their origins, meanings, and example sentences
Word	Origin	Meaning	Example Sentence
Hair follicle	Hair + Latin folliculus	A small structure in the skin where hair grows.	Each hair grows from a hair follicle.
Hair cell	Hair + cell	A sensory cell used for hearing and balance.	Hair cells help the ear detect sound.
Hallucination	Latin hallucinari	A sensory experience that happens without an outside source.	The patient reported a visual hallucination.
Hematology	Greek haima + logos	The study of blood and blood disorders.	She studied hematology at university.
Hemoglobinopathy	Hemoglobin + Greek pathos	A disorder that affects hemoglobin.	Sickle cell disease is a hemoglobinopathy.
Hemorrhage	Greek haima + rhegnynai	Heavy or uncontrolled bleeding.	The injury caused a hemorrhage.
Hepatic	Greek hepar	Related to the liver.	The test showed a hepatic problem.
Hepatitis	Greek hepar + -itis	Inflammation of the liver.	Some viruses can cause hepatitis.
Hepatocyte	Greek hepar + kytos	The main type of cell in the liver.	The drug affected the hepatocyte.
Hepatotoxicity	Hepatic + toxicity	Harm or damage caused to the liver by a substance.	The study tested the drug for hepatotoxicity.
Hereditary	Latin hereditarius	Passed from parents to children through genes.	Some diseases can be hereditary.
Histamine	Greek histos + amine	A chemical involved in immune and allergic reactions.	Histamine can cause itching.
Histology	Greek histos + logos	The study of tissues under a microscope.	The doctor studied the tissue using histology.
Histopathology	Greek histos + pathos + logos	The study of diseased tissues.	Histopathology helped identify the disease.
Hypoxia	Greek hypo + oxys	A condition in which the body does not get enough oxygen.	High altitude can lead to hypoxia.

6. Genetics and Cell Science Words That Start With H

Genetics and cell biology contain many useful science words that start with H. These terms help explain genes, chromosomes, DNA, and cell functions.

Biology H terms, their origins, meanings, and example sentences
Word	Origin	Meaning	Example Sentence
Haplotype	Greek haploos + typos	A group of genetic variants passed together.	The researchers studied the haplotype.
Hemizygous	Greek hemi + zygon	Having only one copy of a particular gene instead of two.	The gene was hemizygous in the sample.
Heterochromatin	Greek heteros + chroma	A tightly packed form of DNA.	Heterochromatin is usually less active.
Heterozygous	Greek heteros + zygon	Having two different versions of a gene.	The plant was heterozygous for the trait.
Histone	Greek histos	A protein that helps package DNA.	DNA wraps around histone proteins.
Homeobox	Homeo + box	A DNA sequence found in genes involved in development.	The gene contains a homeobox.
Homeotic gene	Greek homeosis	A gene that helps control body development.	A homeotic gene can affect body structure.
Homologous chromosome	Greek homologos	One of a matching pair of chromosomes.	Humans have pairs of homologous chromosomes.
Homozygous	Greek homos + zygon	Having two identical versions of a gene.	The plant was homozygous for the gene.
Homology	Greek homologia	Similarity due to a common ancestor.	Scientists found homology between the two structures.
Hormone	Greek horman	A chemical messenger made by the body.	Insulin is an important hormone.
Hormone receptor	Hormone + receptor	A protein that receives a hormone signal.	The hormone receptor detected the signal.
Hox gene	Short for homeobox gene	A gene that helps control body development.	Hox genes help organize body structures.
Hybridization	Greek hybrida	The joining of matching DNA or RNA strands.	DNA hybridization can help find a specific sequence.
Hybridoma	Hybrid + Greek soma	A cell made by joining two different cell types.	Scientists use hybridomas to make antibodies.

NCBI resources define terms such as haploid, haplotype, heterozygous, homozygous, hormone, hybridization, and hybridoma in similar scientific contexts. (NCBI)

7. Earth Science Words That Start With H

Earth science uses H words to describe rocks, soil, water, land, and Earth’s history.

Geology H terms, their origins, meanings, and example sentences
Word	Origin	Meaning	Example Sentence
Halite	Greek halos	A mineral form of sodium chloride.	Halite is also known as rock salt.
Halocline	Greek halos + klinein	A layer where water salinity changes quickly with depth.	Scientists found a strong halocline in the sea.
Hardpan	Hard + pan	A hard layer of soil that can block roots and water.	The tree roots could not easily pass through the hardpan.
Headland	Head + land	A piece of land that extends into a body of water.	Waves hit the rocky headland.
Heat flow	Heat + flow	The movement of heat through Earth’s materials.	Scientists measure heat flow beneath the ocean floor.
Holocene	Greek holos + kainos	The geological epoch in which we currently live.	Humans developed cities during the Holocene.
Horizon	Greek horizon	A layer or boundary in soil or geology.	The soil had a dark upper horizon.
Hot spring	Hot + spring	A natural spring of warm or hot water.	The region has several hot springs.
Humus	Latin humus	Dark organic material found in healthy soil.	Humus helps improve soil quality.
Hydrology	Greek hydor + logos	The study of Earth’s water.	Hydrology helps us understand rivers.
Hydrosphere	Greek hydor + sphaira	All of Earth’s water.	Oceans are part of the hydrosphere.
Hydrothermal vent	Greek hydor + therme	An opening on the seafloor that releases hot water.	Many unusual animals live near hydrothermal vents.
Hydrothermal alteration	Hydrothermal + alteration	Changes in rocks caused by hot water.	Hydrothermal alteration changed the rock minerals.
Hydrograph	Greek hydor + graphein	A graph showing water flow over time.	The hydrograph showed a rise in river flow.
Hydroperiod	Greek hydor + period	The time and pattern that an area holds water.	The wetland has a seasonal hydroperiod.

8. Ecology and Environmental Science Words That Start With H

These science words that start with H are useful for learning about ecosystems, plants, animals, and environmental conditions.

Environmental H terms, their origins, meanings, and example sentences
Word	Origin	Meaning	Example Sentence
Habitat fragmentation	Habitat + fragmentation	The breaking of one habitat into smaller areas.	Roads can cause habitat fragmentation.
Habitat loss	Habitat + loss	The destruction or reduction of a natural habitat.	Deforestation can cause habitat loss.
Halophyte	Greek halos + phyton	A plant that can grow in salty conditions.	Mangroves are halophytes.
Halophilic	Greek halos + philos	Able to live in very salty conditions.	Some bacteria are halophilic.
Harmful algal bloom	Harmful + algal bloom	A rapid growth of algae that can harm an ecosystem.	The harmful algal bloom affected the lake.
Herbivory	Latin herba + vorare	The feeding of animals on plants.	Herbivory can change plant growth.
Heterogeneity	Greek heteros + genos	The presence of different types or conditions in an area.	Forest heterogeneity can support many species.
Heterozygosity	Greek heteros + zygon	Having different gene versions at a genetic location.	High heterozygosity can increase genetic variation.
Host range	Host + range	The organisms that a parasite or pathogen can infect.	The virus has a wide host range.
Host-parasite interaction	Host + parasite	The relationship between a host and a parasite.	Scientists studied the host-parasite interaction.
Hutchinsonian niche	Named after G. Evelyn Hutchinson	The conditions that allow a species to live and reproduce.	The model showed the species’ Hutchinsonian niche.
Hydric soil	Greek hydor	Soil that stays wet for long periods.	Wetlands often have hydric soil.
Hydrophyte	Greek hydor + phyton	A plant adapted to living in water or wet places.	A water lily is a hydrophyte.
Hypersaline	Greek hyper + Latin sal	Having more salt than normal seawater.	The lake is a hypersaline environment.
Humidity	Latin humiditas	The amount of water vapor in the air.	Humidity was high after the rain.

9. Atmospheric and Weather Science Words That Start With H

The atmosphere has many science words that start with H. These terms describe weather, air, water vapor, storms, and temperature.

Geography H terms, their origins, meanings, and example sentences
Word	Origin	Meaning	Example Sentence
Hadley cell	Named after George Hadley	A large pattern of air movement near the equator.	The Hadley cell affects tropical weather.
Hail	Old English hagol	Balls or pieces of ice that fall from clouds.	Hail damaged the crops.
Hailstone	Hail + stone	One piece of falling hail.	A large hailstone hit the window.
Haze	Middle English hasen	Reduced visibility caused by tiny particles in the air.	Haze covered the hills.
Heat index	Heat + index	A measure of how hot the air feels when humidity is included.	The heat index was very high.
Heat island	Heat + island	A warmer area created by built-up urban surfaces.	Cities can develop a heat island effect.
Hydrometeor	Greek hydor + meteōron	Water or ice particles found in the atmosphere.	Snow is a type of hydrometeor.
Hydropower	Greek hydor + power	Electricity made using moving water.	The dam produces hydropower.
Hygrometer	Greek hygros + metron	An instrument used to measure humidity.	The scientist checked the hygrometer.
Hygroscopic	Greek hygros + skopein	Able to absorb moisture from the air.	Salt can be hygroscopic.
Hygroscopicity	Greek hygros	The ability of a material to absorb moisture from air.	The powder has high hygroscopicity.
Hyetograph	Greek hyetos + graphein	A graph that shows rainfall over time.	The engineer studied the hyetograph.
Hurricane	Spanish huracán	A powerful tropical storm with very strong winds.	The hurricane reached the coast.
Hydroclimate	Greek hydor + climate	The climate conditions related to water.	Scientists study hydroclimate changes.
Hydrometeorology	Greek hydor + meteōron	The study of water and weather together.	Hydrometeorology helps predict floods.

10. General Science and Advanced Science Words That Start With H

The final group contains useful terms from different areas of science. They may appear in school lessons, laboratory work, research, and scientific writing.

Chemistry H terms, their origins, meanings, and example sentences
Word	Origin	Meaning	Example Sentence
Hazard	French hasard	Something that can cause harm or danger.	The chemical was marked as a laboratory hazard.
Hazardous	Hazard + -ous	Dangerous or likely to cause harm.	The laboratory stores hazardous chemicals safely.
Heat transfer	Heat + transfer	The movement of heat from one place to another.	Heat transfer occurs between objects at different temperatures.
Heuristic	Greek heuriskein	A method that helps solve a problem or find an answer.	The scientist used a heuristic method to explore the problem.
High-performance liquid chromatography	High-performance + chromatography	A method used to separate substances in a mixture.	The lab used high-performance liquid chromatography.
Homeotic	Greek homeosis	Related to genes that control body-part development.	The mutation caused a homeotic change.
Host galaxy	Host + galaxy	A galaxy containing an astronomical object or event.	Scientists identified the host galaxy of the explosion.
Hubble Space Telescope	Named after Edwin Hubble	A space telescope used to observe distant objects.	The Hubble Space Telescope captured the galaxy.
Hubble tension	Hubble + tension	A difference between some measurements of the universe’s expansion rate.	Scientists are studying the Hubble tension.
Hydrogen ion	Hydrogen + ion	A positively charged hydrogen particle, H⁺.	A high concentration of hydrogen ions makes a solution acidic.
Hydrogen spectrum	Hydrogen + spectrum	The pattern of light produced or absorbed by hydrogen.	Students studied the hydrogen spectrum in physics.
Hydrophobic	Greek hydor + phobos	Not mixing easily with water.	Oil is hydrophobic.
Hypertonic	Greek hyper + tonos	Having a higher concentration of dissolved substances than another solution.	The cell was placed in a hypertonic solution.
Hypothesis	Greek hypothesis	A testable idea that may explain something.	The scientist tested the hypothesis.
Hypotonic	Greek hypo + tonos	Having a lower concentration of dissolved substances than another solution.	Water moved into the cell in the hypotonic solution.

Why Learn Science Words That Start With H?

Learning science words that start with H can make science books and lessons easier to understand. Many H words appear in biology, chemistry, physics, medicine, astronomy, and Earth science.

Some are basic terms, such as heat, habitat, and hydrogen. Others are more advanced, such as homeostasis, heterozygosity, and Hubble constant.

The important thing is not to memorize every difficult definition at once. Learn the word, understand its simple meaning, and then look at how it is used in a sentence.

How to Remember Science Words That Start With H

Here are a few simple ways to remember these terms:

Group similar words together. Learn chemistry words separately from biology words.
Use example sentences. A sentence shows how a term works in real science.
Learn word parts. For example, hydro- often relates to water.
Review difficult terms often. Short study sessions can help you remember them.
Use the words in your own sentences. This can make new vocabulary easier to recall.

Conclusion

This list of 150 science words that start with H covers many areas of science, including biology, chemistry, physics, astronomy, medicine, genetics, ecology, Earth science, and weather.

Words such as hydrogen, habitat, heat, helium, homeostasis, hydrology, hormone, hydrolysis, and Hubble constant are useful examples of how one letter can connect many different scientific fields.

If you are a student, start with the words you see most often in your lessons. Once those become familiar, move on to the more advanced terms.

FAQs About Science Words That Start With H

What is a common science word that starts with H?

Hydrogen is one of the most common. It is the first element on the periodic table and is important in chemistry, biology, and astronomy. NASA describes hydrogen as the lightest and most abundant element in the universe. (NASA Science)

What are some biology science words that start with H?

Some examples are habitat, haploid, haplotype, hemoglobin, hematopoiesis, heterotroph, homeostasis, and host.

What are some chemistry words that start with H?

Examples include hydrogen, hydrogen bond, hydrolysis, hydroxide, hydrocarbon, hydrate, halogen, halide, and hydrogenation.

What are some physics words that start with H?

Some important examples are hadron, half-life, Hall effect, harmonic motion, heat, Hertz, Higgs boson, and hydrodynamics.

What astronomy words start with H?

Astronomy includes habitable zone, Hadean, Haumea, heliosphere, heliopause, Hubble constant, Hubble’s law, hypernova, and hot Jupiter. NASA’s astronomy glossary includes several of these terms. (NASA Science)

What medical science words start with H?

Examples include hematology, hemoglobinopathy, hemorrhage, hepatic, hepatitis, hepatocyte, histamine, histology, and hypoxia.

Why are science words that start with H useful for students?

They help students understand textbooks, class lessons, laboratory activities, research material, and science questions. Learning them by subject makes the vocabulary easier to remember.

What does the prefix “hydro-” mean in science?

The prefix hydro- is commonly related to water. For example, hydrology is the study of water, while a hydrothermal vent is a seafloor opening that releases hot, mineral-rich water.

What is the Hubble constant?

The Hubble constant describes the present rate of expansion of the universe. NASA explains that scientists use different observations to measure this expansion rate. (NASA Science)

What is homeostasis?

Homeostasis is the process of keeping internal body conditions stable. For example, your body changes how it releases heat when your temperature changes.