140 Science Words Starting With H and Their Meanings

Science is full of fascinating ideas, and the words we use to explain them are just as important as the concepts themselves. Learning science words starting with H can open the door to better understanding in physics, chemistry, biology, and more. A strong scientific vocabulary list gives students and professionals the tools to describe processes, share discoveries, and connect ideas across different fields. When you understand the meaning of these words, you can see how they fit into the bigger picture of science.

Many of these scientific terms starting with H have roots in Latin or Greek, which means knowing them can also improve your understanding of other words in the future. From Hertz in physics to homeostasis in biology, each term carries a piece of scientific history. In this guide, we will explore 140 science words beginning with H across different subjects, their meanings, and how they are used. You will find them explained in simple English, making this an easy yet powerful learning resource for school, exams, or curiosity.

Physics Words That Start With H

Word	Meaning	Example
Hertz	A unit of frequency equal to one cycle per second.	A radio signal may be transmitted at 100 Hertz.
Half-life	Time it takes for half of a substance to decay.	The half-life of carbon-14 is 5,730 years.
Harmonic motion	Repeated back-and-forth movement in a regular cycle.	A pendulum shows harmonic motion.
Heat capacity	Amount of heat needed to raise the temperature of a substance.	Water’s heat capacity makes it slow to heat up.
Hydrodynamics	Study of liquids in motion.	Boat design improves using hydrodynamics.
Hydrostatics	Study of fluids at rest.	Dams are designed with hydrostatics in mind.
Holography	Creating 3D images with laser light.	Holography is used in security labels.
Hypersonic speed	Speed over five times the speed of sound.	Some missiles travel at hypersonic speed.
Hall effect	Voltage created when a current moves through a magnetic field.	Sensors use the Hall effect to detect magnets.
Heat transfer	Movement of heat from one place to another.	Heat transfer cooks pasta in boiling water.

Chemistry Words That Start With H

Word	Meaning	Example
Halogen	Element in group 17 of the periodic table.	Chlorine is a halogen.
Heat of reaction	Heat released or absorbed during a reaction.	Combustion has a high heat of reaction.
Hydrocarbon	Compounds made of hydrogen and carbon.	Gasoline is made of hydrocarbons.
Hydrogen bond	Weak bond between molecules due to hydrogen attraction.	Water’s hydrogen bonds give it unique properties.
Hydrate	Compound containing water molecules.	Gypsum is a common hydrate.
Hydrochloric acid	Strong acid found in the stomach.	Hydrochloric acid helps digest food.
Heavy metals	Dense metals are often toxic in high amounts.	Lead is a harmful heavy metal.
Homogeneous mixture	Evenly mixed substance.	Salt water is a homogeneous mixture.
Hydrochloride	Chemical form of a compound combined with hydrochloric acid.	Many medicines are hydrochlorides.
Helium gas	Light, non-reactive gas.	Helium gas fills balloons.

Biology Words That Start With H

Word	Meaning	Example
Homeostasis	Maintaining internal balance in living things.	Sweating helps maintain homeostasis.
Heredity	Passing of traits from parents to offspring.	Eye color is determined by heredity.
Hormone	Chemical messenger in the body.	Insulin is a hormone that controls blood sugar.
Hemoglobin	Protein in blood that carries oxygen.	Hemoglobin makes blood red.
Habitat	Natural home of a living thing.	Forests are the habitat for many birds.
Herbivore	Animals that eat only plants.	Cows are herbivores.
Heterozygous	Having two different genetic traits.	A pea plant can be heterozygous for flower color.
Homologous structures	Similar body parts in different species.	Whale fins and human arms are homologous structures.
Human genome	Complete set of human DNA.	Scientists study the human genome to learn about diseases.
Hydrolysis	Breaking molecules apart with water.	Digestion uses hydrolysis to break down food.

Earth & Environmental Science Words That Start With H

Word	Meaning	Example
Hydrosphere	All water on Earth.	Oceans are part of the hydrosphere.
Humus	Organic part of soil.	Humus makes soil fertile.
Hurricane	A large storm with strong winds and rain.	Hurricanes can cause flooding.
Hydrothermal vent	Hot water opening on the ocean floor.	Unique life forms live near hydrothermal vents.
Hydrology	Study of water movement.	Hydrology helps predict floods.
Heat island effect	Cities being hotter than nearby areas.	The heat island effect makes summers warmer in cities.
Hazardous waste	Dangerous waste material.	Factories must safely dispose of hazardous waste.
Humidity	Amount of water vapor in the air.	Humidity rises before a storm.
Hailstorm	Storm producing balls of ice.	The hailstorm damaged crops.
Habitat loss	Destruction of natural environments.	Deforestation causes habitat loss.

Math & Measurement Words That Start With H

Word	Meaning	Example
Hypotenuse	Longest side of a right triangle.	The hypotenuse is opposite the right angle.
Harmonic mean	Special type of average.	The harmonic mean is used in physics.
Hyperbola	Curve with two separate parts.	Satellite paths can form a hyperbola.
Histogram	Bar chart showing data distribution.	A histogram shows test score ranges.
Hexadecimal	Number system using base 16.	Computers use hexadecimal codes.
Hypothesis testing	Statistical method to test a claim.	Scientists use hypothesis testing in experiments.
Hierarchy	System of ranking.	The food chain is a hierarchy.
Horizontal axis	The x-axis in a graph.	Time is shown on the horizontal axis.
Hyperbolic function	Function based on hyperbola properties.	Engineers use hyperbolic functions in design.
Half-angle formula	Trigonometric identity for angles.	The half-angle formula is used in geometry.

Forensic Science Words That Start With H

Word	Meaning	Example
Handwriting analysis	Examining writing to find authorship.	Police used handwriting analysis in the case.
Hematology	Study of blood.	Hematology helps diagnose anemia.
Hair analysis	Examining hair for identity or drug use.	Forensics used hair analysis to solve the crime.
Human remains identification	Determining identity from the body remains.	DNA aids in human remains identification.
Heat signature	Infrared image showing heat from a body.	Drones detect heat signatures at night.
Homicide investigation	Process of solving a murder case.	Evidence is vital in homicide investigations.
High-resolution imaging	Detailed image capture.	High-resolution imaging helps identify fingerprints.
Hazardous material testing	Checking dangerous substances.	Airports use hazardous material testing.
Handgun residue analysis	Detecting gunpowder on suspects.	Forensics used handgun residue analysis in court.
Handprint recognition	Identifying a person by their handprint.	Security systems use handprint recognition.

Hydrology & Water Science Terms

Word	Meaning	Example
Hydrology	Study of water on Earth	Hydrology examines rivers, lakes, and groundwater.
Hydrosphere	All water bodies on Earth	Oceans are part of the hydrosphere.
Hydrothermal	Related to heated water	Hydrothermal vents support unique marine life.
Hydrate	Compound with water molecules	Copper sulfate hydrate is blue in color.
Hydraulic	Operated by liquid pressure	Hydraulic systems are used in cranes.
Hydrostatic	Related to fluids at rest	Hydrostatic pressure increases with depth.
Hydrograph	Chart showing water levels	The hydrograph indicated rising river levels.
Hydrometer	Device to measure liquid density	A hydrometer tests sugar content in wine.
Hydrolysis	Chemical breakdown with water	Hydrolysis splits fats into glycerol and fatty acids.
Hydrodynamics	Study of liquids in motion	Hydrodynamics explains ship movement.

Astronomy & Space Science Terms

Word	Meaning	Example
Heliosphere	Solar wind bubble around the Sun	The heliosphere protects Earth from cosmic rays.
Heliocentric	Sun-centered model of the solar system	Copernicus proposed the heliocentric theory.
Horizon	Line where sky meets Earth	Stars rise and set at the horizon.
Hypersonic	Speed greater than five times sound	Some spacecraft travel at hypersonic speeds.
Hydrogen	Lightest and most abundant element	Stars are powered by hydrogen fusion.
Halo (Astronomy)	Ring around celestial objects	A halo can be seen around the Moon.
Hypernova	Extremely energetic star explosion	Hypernovae are more powerful than supernovae.
Hubble Constant	Rate of universe expansion	The Hubble Constant helps estimate cosmic age.
Helium	Gas formed in stars by fusion	Helium balloons float because helium is lighter than air.
Hot Jupiter	Giant exoplanet close to its star	Astronomers discovered a new hot Jupiter.

Geology & Earth Science Terms

Word	Meaning	Example
Humus	Decayed plant matter in soil	Humus enriches the soil for farming.
Hill	Elevated area of land	The hill was formed by ancient volcanic activity.
Horizon (Soil)	Layer in soil profile	The A horizon contains topsoil.
Hydrothermal Vent	Sea floor hot spring	Hydrothermal vents host unusual life forms.
Hardness	Resistance of mineral to scratching	Diamond has the highest hardness.
Hydration	Addition of water to a mineral	Hydration changes mineral structure.
Hurricane	Large storm system over oceans	The hurricane caused widespread flooding.
Hoodoo	Tall, thin rock spire	Hoodoos are common in desert landscapes.
Hornfels	Metamorphic rock formed by heat	Hornfels form near magma intrusions.
Hematite	Iron-rich mineral	Hematite is used in steelmaking.

Forensic Science Terms

Word	Meaning	Example
Handwriting Analysis	Study of handwriting for identification	Police used handwriting analysis in the case.
Hair Analysis	Examining hair for evidence	Hair analysis revealed drug traces.
Heat Signature	Thermal image of a body/object	The drone detected a heat signature in the forest.
Hematology	Study of blood	Hematology tests help diagnose diseases.
Homicide Investigation	Process of solving murder cases	The homicide investigation lasted months.
Human Remains Identification	Process of identifying deceased persons	DNA was used for human remains identification.
Hazardous Material Testing	Checking dangerous chemicals	Hazardous material testing is vital for safety.
High-resolution Imaging	Detailed imaging technology	High-resolution imaging revealed hidden fingerprints.
Handprint Analysis	Examining hand impressions	Handprint analysis linked the suspect to the scene.
Hypothesis Testing (Forensics)	Statistical method for evidence analysis	Hypothesis testing confirmed the forensic findings.

Medical & Life Science Terms

Word	Meaning	Example
Homeostasis	Body’s balance of functions	Sweating helps maintain homeostasis.
Hemoglobin	Protein that carries oxygen in blood	Low hemoglobin causes anemia.
Hormone	Chemical messenger in body	Insulin is a hormone that controls sugar levels.
Heredity	Passing traits from parents to children	Eye color is determined by heredity.
Habitat	Natural home of an organism	The forest is the habitat of tigers.
Herbivore	Plant-eating animal	A rabbit is a herbivore.
Heterozygous	Different gene forms in a pair	Heterozygous genes affect traits in offspring.
Homologous Structures	Similar structures in different species	Wings of bats and arms of humans are homologous structures.
Human Genome	Complete set of human DNA	The human genome project mapped our DNA.
Hydrolysis	Breaking down compounds with water	Hydrolysis is important in digestion.

Mathematics & Measurement Terms

Word	Meaning	Example
Hypotenuse	Longest side of a right triangle	The hypotenuse is opposite the right angle.
Harmonic Mean	Type of average	The harmonic mean is used in physics.
Hyperbola	Curve with two branches	Satellite paths can form a hyperbola.
Histogram	Graph showing frequency data	The histogram showed the class test results.
Hexadecimal	Base-16 number system	Computers use hexadecimal codes.
Hypothesis Testing	Statistical testing method	Hypothesis testing is common in research.
Hierarchy	Ranking system	Biological taxonomy is a hierarchy.
Horizontal Axis	X-axis in a graph	Time is plotted on the horizontal axis.
Hyperbolic Function	Math function related to hyperbolas	Hyperbolic functions appear in physics.
Half-Angle Formula	Trigonometric formula	The half-angle formula helps solve equations.

Environmental Science Terms

Word	Meaning	Example
Hydrosphere	All Earth’s water	The hydrosphere covers about 71% of Earth.
Habitat Loss	Destruction of living spaces	Deforestation causes habitat loss.
Humidity	Amount of water vapor in air	High humidity makes the air feel warmer.
Hailstorm	Storm with hail	The hailstorm damaged crops.
Heat Island Effect	Urban areas becoming warmer	Cities suffer from the heat island effect.
Hazardous Waste	Dangerous byproducts	Hazardous waste must be disposed of safely.
Hurricane	Large ocean storm	The hurricane caused flooding in coastal towns.
Hydrology	Study of Earth’s water	Hydrology helps manage water resources.
Hydrothermal Activity	Heated water processes	Hydrothermal activity occurs in volcanic regions.
Hydroelectric Power	Energy from moving water	Dams produce hydroelectric power.

Technology & Engineering Terms

Word	Meaning	Example
Holography	Creating 3D images with light	Holography is used in security printing.
Heat Capacity	Amount of heat needed to raise temperature	Water has high heat capacity.
Hall Effect	Voltage difference in a conductor in a magnetic field	Hall effect sensors are used in electronics.
Hydraulic System	Uses pressurized fluids to work	Cranes use hydraulic systems.
Hybrid Engine	Combines two power sources	Hybrid cars use electric and fuel engines.
Heat Exchanger	Transfers heat between substances	Heat exchangers are used in power plants.
High-voltage Engineering	Study of high electrical voltages	High-voltage engineering is key in transmission lines.
Heat Treatment	Changing metal properties by heating	Steel hardens after heat treatment.
Hydrodynamic Bearing	Bearing that uses fluid film for motion	Hydrodynamic bearings reduce friction in turbines.
Hypersonic Technology	Technology for extreme speeds	Hypersonic jets can travel faster than sound.

Conclusion

Expanding your science vocabulary with H builds confidence in reading textbooks, following lessons, and taking exams. From Hertz in physics to habitat loss in environmental science, each term is a key that unlocks deeper understanding. These science words that start with H and meanings are not just academic—they apply to real-world situations, experiments, and discoveries.

If you keep practicing with this glossary of science terms, your knowledge will grow naturally. Use them in conversations, writing, and research. Science is a language, and mastering it starts with learning the words that shape it.