List of Words for Letter ‘A’
Click on 
to hear the word and definition
-
abiotic The effects on the ecosystem that are a result of the nonliving parts of that ecosystem.
-
acceleration A
change in the velocity of an object over time.
-
acid A substance that has a pH below 7, tastes sour, and turns blue litmus paper pink or red.
-
acid rainAcid that is formed when the sulfur and nitrogen gases produced by burning fossil fuels combine with water vapor in the air and then fall to Earth as rain.
-
acquired A trait influenced by experience or the environment.
-
active transport The movement of materials through a cell membrane, which requires energy.
-
adaptation A
change in an organism that helps it survive or reproduce in its environment.
-
aftershock Smaller earthquakes that follow a major earthquake.
-
air mass A large region of the atmosphere in which the air has similar properties throughout.
-
air pressure The force exerted on a given area by the weight of the air above it.
-
alloy A mixture of one or more metals with other solids.
-
amplitude The
height of a wave from its trough or crest to its midpoint.
-
antibiotic A
medicine that kills disease–causing bacteria without harming the host.
-
aquifer An
underground area of rock and soil filled with water that is squeezed between tightly packed layers of rock.
-
asteroid A
rocky or metallic object that orbits the Sun.
-
astronomy The
study of the universe.
-
atmosphere The
layer of gases that surround Earth.
-
atom The smallest particle of an element that still has the same chemical properties of the element.
-
atomic The
number of protons in an atom of an element.