Longman Dictionary of Contemporary English homepage

Date: 1500-1600
Language: Latin
Origin: atomus, from Greek, from atomos 'that cannot be divided', from temnein 'to cut'

atom

noun
     
Related topics: Physics
at‧om [countable]
1HP the smallest part of an element that can exist alone or can combine with other substances to form a molecule:
carbon atoms
atom of
two atoms of hydrogen
2 a very small amount of something - used for emphasis
atom of
There isn't an atom of truth in it.

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