'antilogic' originates from Greek elements, specifically 'anti-' and 'logos', where 'anti-' meant 'against' and 'logos' meant 'reason'.

'antilogic' was formed in Modern English by combining the prefix 'anti-' with 'logic' (from Latin 'logica', from Greek 'logikē'), creating a compound meaning 'against logic'.

Initially it simply meant 'against logic' as a literal compound; over time it has been used more broadly to describe ideas, arguments, or behavior regarded as irrational or unreasonable.