If you’ve got a science assignment, a vocabulary quiz, or you’re just building your science word knowledge — this is the right place. The letter C covers an enormous range of science, from biology and chemistry to space and the human body. Every word below is real, accurate, and explained in plain English.
Biology Science Words That Start With C
Camouflage
When an animal blends into its surroundings to hide from predators or prey. A chameleon changing color is camouflage in action.
Capillary
The tiniest blood vessels in the body. So narrow that red blood cells pass through single-file. This is where oxygen moves from blood into your tissues.
Carbohydrate
A major energy source for living things, made of carbon, hydrogen, and oxygen. Sugar, starch, and fiber are all carbohydrates.
Carnivore
An animal that eats only other animals.
Root clue: carne (Latin) = flesh/meat. A carnivore is literally a “meat eater.”
Cell
The smallest unit of life. Every living organism is made of at least one cell. Bacteria are single-celled; humans have around 37 trillion.
Chlorophyll
The green pigment inside plant cells that absorbs sunlight for photosynthesis. It’s also why plants are green.
Chloroplast
The organelle inside plant cells where photosynthesis actually happens. It contains chlorophyll.
Think of it as the plant’s solar panel.
Chromosome
A tightly coiled structure of DNA inside a cell nucleus that carries genetic information.
Root clue: chroma (color) + soma (body) — named because chromosomes absorb dye easily and become visible under a microscope.
Cilia (SIL-ee-ah)
Tiny hair-like structures on the surface of certain cells. They sweep fluids and particles along — like the cilia lining your airways that push mucus and dust away from your lungs.
Cloning
Producing a genetically identical copy of an organism or cell. Dolly the sheep, born in 1996, was the first mammal cloned from an adult cell.
Conifer
A tree or shrub that produces seeds in cones and usually has needle-like leaves. Pine, spruce, and fir are conifers. Most are evergreen.
Cortex
The outer layer of an organ or structure. The brain has a cerebral cortex. Plant roots have a root cortex.
Cotyledon (kot-ih-LEE-don)
The seed leaf inside a plant embryo. It provides food for the seedling until it can photosynthesize on its own.
Cytoplasm (SY-toh-plaz-um)
The gel-like fluid that fills a cell and surrounds its organelles. Most of the cell’s chemical activity takes place here.
Chemistry Science Words That Start With C
Carbon
A non-metallic element (symbol: C, atomic number 6) that forms the chemical backbone of all living things. Also found in coal, diamonds, and CO₂.
Catalyst (KAT-uh-list)
A substance that speeds up a chemical reaction without being consumed in the process. Enzymes in your body act as biological catalysts.
Combustion
A chemical reaction where fuel burns in oxygen and releases heat and light. Your car engine runs on combustion. So does a candle flame.
Compound
A substance formed when two or more different elements bond chemically. Water (H₂O) and table salt (NaCl) are both compounds.
Concentration
How much of a substance is dissolved in a given volume of solution. A strong cup of coffee has a high concentration of caffeine.
Condensation
When a gas cools and becomes a liquid. The water droplets on a cold glass on a warm day are condensation — water vapor from the air turning liquid.
Corrosion
The gradual breakdown of a material through chemical reactions, usually with oxygen or moisture. Rust is iron corrosion.
Covalent Bond (koh-VAY-lent)
A chemical bond where two atoms share electrons. Found in molecules like water (H₂O) and carbon dioxide (CO₂).
Crystal
A solid where atoms are arranged in a precise, repeating three-dimensional pattern. Salt, sugar, ice, and diamonds are all crystals.
Physics Terms that start with c
Centripetal Force (sen-TRIP-ih-tal)
The inward force that keeps an object moving in a curved or circular path. When you swing a ball on a string in a circle, the tension in the string is the centripetal force.
Circuit
A closed path through which electric current flows. Break the path anywhere and the current stops — which is how a light switch works.
Coherent Light
Light waves that travel perfectly in sync — same direction, same wavelength. Laser beams are coherent light.
Compression
A force that squeezes or pushes matter together. When you press down on a spring, you’re applying compression.
Conduction
The transfer of heat or electricity through a material by direct contact. Metal conducts heat well — that’s why a metal spoon in hot soup gets warm quickly.
Convection
Heat transfer through the movement of a fluid (liquid or gas). Hot air rises, cooler air sinks to replace it, creating a convection current.
Coulomb (KOO-lom)
The SI unit of electric charge, named after physicist Charles-Augustin de Coulomb.
Current
The flow of electric charge through a conductor, measured in amperes (A). The higher the current, the more charge is moving per second.
Read more: Science Words That Start With S | Full List with Meanings
Earth Science Words That Start With C
Calcite
A common mineral made of calcium carbonate (CaCO₃). It’s the main component of limestone and marble.
Canyon
A deep, narrow valley with steep sides carved by a river over millions of years. The Grand Canyon is one of the most famous examples on Earth.
Carbon Cycle
The continuous movement of carbon through the atmosphere, oceans, soil, and living organisms. Plants absorb CO₂; animals release it through respiration.
Carrying Capacity
The maximum number of individuals an environment can support with its available food, water, and space.
Example: if a forest can feed 200 deer, that’s its carrying capacity for deer.
Climate
The average weather conditions of a region measured over many decades. Not what’s happening outside today — that’s weather.
Compaction
When layers of sediment are pressed together under pressure and form sedimentary rock over time.
Conglomerate (kon-GLOM-er-it)
A type of sedimentary rock made of rounded rock fragments cemented together by finer material. It looks like a rocky pudding.
Continental Drift
The slow movement of Earth’s continents over millions of years. Once a single supercontinent called Pangaea, they’ve slowly drifted to their current positions.
Core
Earth’s innermost layer. The outer core is liquid iron and nickel. The inner core is solid iron and nickel, despite extremely high temperatures, because of immense pressure.
Crater
A bowl-shaped depression formed by a meteorite impact or a volcanic eruption. The Moon’s surface is covered in impact craters.
Crust
The thin, outermost layer of the Earth. The oceanic crust (under oceans) is thinner and denser than the continental crust (under landmasses).
Cyclone
A large rotating storm system with low atmospheric pressure at its center. Hurricanes and typhoons are types of cyclones.
Space & Astronomy
Celestial (seh-LES-chul)
Relating to the sky or outer space. Stars, planets, moons, and comets are all celestial bodies.
Comet
A small icy body that orbits the sun. When a comet passes close to the sun, solar heat vaporizes its ice and creates a glowing tail that always points away from the sun.
Constellation
A named pattern of stars as seen from Earth. There are 88 officially recognized constellations, including Orion, Leo, and Ursa Major.
Corona
The outermost layer of the sun’s atmosphere. It’s usually invisible but appears as a glowing ring during a total solar eclipse. Surprisingly, the corona is hotter than the sun’s surface.
Cosmic Ray
High-energy particles traveling through space at nearly the speed of light. Earth’s magnetic field and atmosphere protect us from most of them.
Cosmos
The universe understood as an ordered, complex system — all matter, energy, space, and time together.
Human Body & Medical Terms that start with c
Capillary Action
The ability of liquid to flow through narrow spaces against gravity, driven by surface tension and adhesion. Plants use capillary action to pull water up through their stems.
Cartilage (KAR-tih-lij)
A firm but flexible connective tissue found in ears, the nose, and joints. Unlike bone, it has no blood vessels.
Coagulation (koh-ag-yoo-LAY-shun)
The process by which blood clots to stop bleeding. When you cut yourself, coagulation forms a clot within minutes.
Cochlea (KOK-lee-ah)
A spiral-shaped structure in the inner ear that converts sound vibrations into nerve signals sent to the brain.
Think of it as the ear’s microphone.
Cornea
The clear, dome-shaped outer layer of the eye that focuses incoming light before it reaches the lens.
Cortisol (KOR-tih-sol)
A hormone released by the adrenal glands during stress. It raises blood sugar, suppresses inflammation, and prepares the body for a fast response.
Cranium
The bony case that surrounds and protects the brain. It forms the upper and back part of the skull.
Environmental Science
Carbon Footprint
The total amount of greenhouse gases — especially CO₂ — produced by a person, product, or activity. Flying, driving, and heating a home all contribute.
Conservation
The protection and careful management of natural resources and ecosystems to prevent depletion and extinction.
Composting
The natural breakdown of organic waste (food scraps, leaves) by bacteria and fungi into nutrient-rich material that improves soil.
Commonly Confused C Words
Climate vs. Weather
Weather is what’s happening outside right now. Climate is the average pattern over 30+ years. A desert has a dry climate — but it can still have a rainy day.
Conduction vs. Convection
Both transfer heat — but differently. Conduction is heat moving through direct contact (metal spoon in soup). Convection is heat moving through fluid movement (hot air rising from a heater).
Comet vs. Asteroid
Comets are icy and develop glowing tails near the sun. Asteroids are rocky, have no tails, and mostly orbit between Mars and Jupiter.
Chromosome vs. Chromatin
Chromatin is the loose, uncoiled form of DNA in a resting cell. When the cell prepares to divide, that chromatin condenses and coils tightly into visible chromosomes.
Carnivore vs. Omnivore vs. Herbivore
Carnivores eat only animals. Herbivores eat only plants. Omnivores eat both.
Humans are omnivores. Dogs are technically omnivores too.
Read also: Science Words That Start With T | Meanings, Examples
Quick Reference for Science Words That Start With C
| Word | Field | Meaning |
| Cell | Biology | Smallest unit of life |
| Carbohydrate | Biology | Energy molecule in food |
| Chromosome | Biology | DNA-carrying structure in a cell nucleus |
| Carbon | Chemistry | Element in all living things |
| Catalyst | Chemistry | Speeds up chemical reactions |
| Combustion | Chemistry | Burning — fuel reacting with oxygen |
| Condensation | Chemistry | Gas cooling into a liquid |
| Current | Physics | Flow of electric charge |
| Conduction | Physics | Heat transfer by direct contact |
| Convection | Physics | Heat transfer through fluid movement |
| Climate | Earth Science | Long-term weather pattern of a region |
| Continental Drift | Earth Science | Slow movement of Earth’s continents |
| Crater | Earth Science | Bowl-shaped depression from impact or eruption |
| Comet | Astronomy | Icy space body with a glowing tail |
| Corona | Astronomy | Outermost layer of the sun’s atmosphere |
| Cortisol | Medical | Stress hormone from the adrenal glands |
| Cochlea | Medical | Spiral ear structure that processes sound |
| Conservation | Environment | Protection of natural resources |
Science vocabulary builds on itself — once you understand cell, words like cytoplasm, chromosome, and chloroplast start making sense because they all connect back to it. The same goes for carbon, which threads through chemistry, biology, environmental science, and earth science all at once. Start with the words your course uses most, and the others will click into place naturally.
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