Main Entry: at·om

Pronunciation: \ˈa-təm\

Function: noun

Etymology: Middle English, from Latin atomus, from Greek atomos, from atomos indivisible, from a- + temnein to cut

Date: 15th century

1 : one of the minute indivisible particles of which according to ancient materialism the universe is composed
2 : a tiny particle : bit
3 : the smallest particle of an element that can exist either alone or in combination
4 : the atom considered as a source of vast potential energy