English

subatom

From sub- + atom.

Formed from sub- + atom

Proto-Indo-European *upó ‘up; from below’

Proto-Italic *supo ‘under’

Latin sub ‘under, beneath, below’

English sub-

Proto-Indo-European *temh₁- ‘to cut’

…

Ancient Greek ἄτομος ‘indivisible’

Latin atomus ‘smallest particle’

Middle French athome

Middle English attome

English atom

Today it means

noun Any particle that is smaller than an atom; a subatomic particle.

Language periods are conventional ranges, not dates for this word.