'antiradicalism' originates from Modern English, specifically the combination of the prefix 'anti-' (from Greek 'anti-' meaning 'against') and the noun 'radicalism' (from 'radical' + '-ism'), where 'anti-' meant 'against' and 'radical' originally related to 'root'.

'antiradicalism' formed by attaching the prefix 'anti-' to 'radicalism'. 'Radical' comes from Latin 'radicalis' (from 'radix' meaning 'root'), passed through Old French/Medieval Latin into English; 'radicalism' arose by adding the English suffix '-ism', and 'antiradicalism' developed in modern usage (19th–20th century) as a term for opposition to radicals.

Initially it meant 'opposition to radical political movements' and over time the core meaning has remained similar, though it may be applied more broadly to opposition to extreme change in various contexts.