Back to: Science California Science Grade 5 e-Glossary A

List of Words for Letter ‘A’

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absorption a process in which something is taken in and used, as by a cell
acid a substance that tastes sour, sharp or biting
acidity the strength of a acidic solution
aerial root a root that never touches the ground
aerobic having to do with the use of oxygen
air mass a large region of air that has a similar temperature and humidity
air pressure the force put on a given area by the weight of the air above it
algae a plantlike protist that lives in a water environment
alkali metal an element in the most reactive family of metals
alkalinity the strength of a base solution
alloy a mixture of two or more elements, usually metals
altitude how high something is above Earth's surface
alveoli thin-walled air sacs within the lungs
amoeba a common animal-like protist that changes shape to catch food
amphibian a vertebrate animal that spends part of its life in water and part on land
anaerobic requiring energy without an increase in oxygen
angiosperm a seed plant that produces flowers
anus the opening through which solid waste leaves the body
aorta the large artery that carries blood away from the heart and to the rest of the body
aqueduct a structure that carries large amounts of water from one place to another
aquifer an underground layer of rock, sand, or gravel that contains water
artery a blood vessel that carries blood away from the heart
arthropod an invertebrate animal with a hard outer skeleton, a segmented body, and jointed legs
artificial made by man, but working like the natural thing
asteroid a large piece of rock or metal in space
astronomical unit the distance between the Earth and the Sun
atmosphere all of the air surrounding the Earth
atom the smallest particle of an element that has the properties of that element
atomic number the number of protons in a single atom of an element
atomic weight a measure of the mass of a single atom of an element
atrium an upper chamber of the human heart
aurora borealis colored lights seen in the upper atmosphere of the northern hemisphere