'anti-atom' originates from Modern English, formed from the prefix 'anti-' (from Greek 'anti-' meaning 'against, opposite') and 'atom' (from Greek 'atomos' meaning 'indivisible').

'atom' comes from Greek 'atomos' (literally 'uncut, indivisible'), which passed into Latin and then Middle English as 'atom'. The prefix 'anti-' comes from Greek 'anti-'. The compound 'antiatom' or 'anti-atom' arose in 20th-century scientific English with the development of antimatter research.

Initially 'atom' meant an indivisible particle; with modern physics and the prefix 'anti-' the compound came to mean the antiparticle counterpart of an atom (an atom made of antiparticles).