'antireactive' originates from Modern English, specifically formed by combining the prefix 'anti-' (from Greek 'anti' meaning 'against') with the adjective 'reactive' (from 'react' + suffix '-ive').

'reactive' developed from the verb 'react,' which ultimately traces to Latin elements 're-' + 'agere' ('to do, act') and entered English via Late Latin and French; 'anti-' comes from Greek 'anti' and entered English through Latin/Old French. 'Antireactive' is a Modern English coinage formed by combining these elements rather than by direct evolution from a single older word.

The components originally meant 'against' ('anti-') and 'tending to react' ('reactive'); combined in Modern English the compound now means 'against or inhibiting reactivity' (either chemical reactivity or, by extension, responsiveness).