'antimodernness' originates from the combining of the Greek prefix 'anti-' (from Greek 'anti', meaning 'against'), the adjective 'modern' (from Latin 'modernus'), and the English nominalizing suffix '-ness' (from Old English 'nes(s)', meaning 'state or quality').

'anti-' reached English via Latin and Old French from Greek 'anti'; 'modern' comes from Late Latin 'modernus' (from Latin 'modo' meaning 'just now'), which passed into French as 'moderne' and then into English; the suffix '-ness' is native to Old English. These elements were combined in English to form 'antimodernness' as a compound describing the quality of being anti-modern.

Initially the prefix and root simply meant 'against' + 'pertaining to the present or recent time'; over time the compound came to denote specifically the disposition or quality of opposing modern ideas, practices, or aesthetics.