atom

Meanings

1. 1
   noun

   The smallest part of a chemical element that can exist.

   Three oxygen atoms join together to form the molecule ozone.

2. 2
   noun

   A very small amount of something.

   There wasn't an atom of truth in what he said.

From Middle English attome, from Middle French athome, from Latin atomus (“smallest particle”), from Ancient Greek ἄτομος (átomos, “indivisible”), from ἀ- (a-, “not”) + τέμνω (témnō, “to cut”, o-grade in τομ-) + -ος (-os). Atoms are so named because they were historically thought up as to be the smallest unit of matter, and thus indivisible. Doublet of atomus.

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