Science Definitions by GradeScience Definitions by Grade



Absorb: To take in.

Abyssal Plain: The vast floor of the deep oceans.

Air Mass: A large body of air that has the same characteristics throughout.

Air Pressure: The weight of air pressing down on an area.

Arctic: A place with a cold, windy environment where the land is covered with ice and snow for most of the year. Only a few plants can grow in the Arctic.

Atmosphere: The air that surrounds the Earth.

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Biodiesel Fuel: A renewable energy source made from natural materials such as animal waste or corn, soybeans and other plants.

Biome: A region of the world that is defined by its climate and the unique plants and animals that live there.

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Carbon Cycle: The flow of carbon dioxide and oxygen through Earth's ecosystems.

Carbon Dioxide (CO2): A gas that is produced by all animals and plants during respiration and used by plants during photosynthesis. Carbon dioxide is also the by-product of burning fossil fuels.

Carbon Emissions: Carbon that is released into the air through the burning of fossil fuels such as coal, gas or oil.

Climate: A region of the earth having specified climatic conditions, the average course or condition of the weather over a period of years.

Cloud: A mass of tiny droplets of water that condensed from the air.

Composting: Using a mixture of plant-based waste to fertilize, or enrich, the soil.

Condensation: The change in form water goes through when it turns from a gas to a liquid.

Conserve: To avoid wasteful use; also, to maintain (a quantity) constant during a process of chemical, physical, or evolutionary change.

Convergent Boundary: A boundary where crustal plates collide with each other.

Convert: To alter the physical or chemical nature or properties of something.

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Desert: An environment that gets little rain. Only a few kinds of plants and animals live in the desert.

Dinosaur: One of a large group of reptiles that lived millions of years ago.

Divergent Boundary: A boundary where crustal plates move away from each other.

Drought: A long time without rain.

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Ecosystem: A community and the abiotic parts of its environment.

Efficiency: The ratio of the work that comes out of a machine to the work put into that machine.

Endangered: In danger of not being alive any more. Sea turtles are endangered animals.

Energy: Something that can cause change and do work. Light and heat are kinds of energy.

Environment: All the living and nonliving things that are around a living thing.

Erosion: The movement or transportation of sediment to new locations.

Evaporate: To change from a liquid to a vapor.

Extinct: When all animals of one kind die; no longer existing as a species.

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Fossil: What is left of a plant or an animal that lived long ago. A fossil can be a print or an animal's teeth, bones, or

Fossil Fuel: An energy rich deposit of coal or petroleum that is the fossilized remains of dead plants and animals.

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Geothermal: Heat that comes from the Earth’s interior.

Global Warming: A warming of the Earth’s atmosphere and oceans.

Greenhouse Effect: Refers to a process in which the sun’s energy is trapped by excessive amounts of certain gases, such as carbon. The result is a warmed atmosphere, similar to the effect of energy trapped in a greenhouse for plants.

Greenhouse Gases: Components in Earth's atmosphere—including water vapor, carbon dioxide, methane, nitrous oxide, and ozone—that contribute to the greenhouse effect. These gases help keep the sun's light energy close to Earth rather than reflecting back into space. Without greenhouse gases, Earth would be too cold to live on.

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Habitat: A place where an animal finds the things it needs to live. In its habitat an animal finds food, water, and shelter.

Heat: The transfer of thermal energy.

Hurricane: A large, spiraling storm system with strong winds, high ocean waves, and heavy rain. Can be as wide as 600 kilometers.

Hybrid Vehicle: A vehicle such as a car that uses a combination of two energy sources, such as gasoline and electricity.

Hydropower: energy that is generated by water power.

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Liquid: A form of matter that does not have its own shape. Water, milk, juice, and gasoline are each a liquid.

Lithosphere: The cool, solid portion of Earth that includes all of the crust and part of the upper mantle.

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Melt: To change from a solid to a liquid.

Meteorologist: A scientist who studies the atmosphere with a particular focus on weather and forecasting.

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Natural Resource: A material that comes from the earth and can be used by living things, for example: water, oil, and minerals.

Nitrogen Cycle: The movement of nitrogen through ecosystems.

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Ocean: A large, deep body of salt water.

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Paleontologist: A scientist who finds and studies fossils. Some paleontologists study dinosaurs.

Pollution: Harmful waste.

Precipitation: The falling of water in the form of rain, sleet, hail, or snow.

Prehistoric: Dated before human records.

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Rain Forest: A forest that is wet all year.

Recycle: To use old materials to make new things.

Reflect: To bounce back light. Refract: To bend or change the direction of light.

Renewable Resources: Resources that can be replaced within a human life span.

Reuse: To use again.

Rock Cycle: A process by which rocks are formed from one another.

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Season: A period of the year with a certain level of temperature and type of weather.

Seismograph: An instrument that measures and records the Earth's vibrations.

Soil: The loose top layer of the Earth's surface. People use soil to grow food.

Solar: Of the sun.

Solar Energy: Light and heat from the sun. Plants and animals on Earth are warmed by solar energy.

Sustainable: Refers to methods of using resources that do not deplete or permanently damage the resource.

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Taiga: A biome where winters are very cold and long and the dominant plants are conifers

Temperature: Degree of hotness or coldness measured on a definite scale.

Thunderstorm: A storm with rain, thunder, and lightning.

Tundra: A place with a cold and windy environment with no trees. The land is covered with ice and snow for most of the year.

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Vapor: Diffused matter (as smoke or fog) suspended floating in the air and impairing its transparency; a gas.

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Water Cycle: The movement of water from the Earth to the sky and back again.

Water Vapor: Water that has changed into a gas.

Weather: The state of the atmosphere with respect to heat or cold, wetness or dryness, calm or storm, clearness or cloudiness.

Wind: Moving air.

Wind Turbine: a high tower with large, fanlike blades; used to convert, or change, wind power into electricity.