'antigay' originates from Greek and English: the prefix 'anti-' ultimately from Greek 'antí' meaning 'against', combined with English 'gay' (from Old French 'gai', originally meaning 'joyful', later used in modern English to mean 'homosexual').

'antigay' changed from the hyphenated form 'anti-gay' (20th century usage) and eventually became used also in the unhyphenated form 'antigay'. The element 'gay' shifted from Old French 'gai' ('joyful') to modern English 'gay' ('homosexual'), which enabled the modern compound.

Initially, the parts meant 'against' (anti-) and 'joyful' (gai), but in modern usage the compound has come to mean 'opposed to homosexuality' or 'opposed to gay people/rights'.