'antihygienic' originates from Modern English, formed from the prefix 'anti-' and the adjective 'hygienic'; 'anti-' ultimately from Greek 'antí' meaning 'against', and 'hygienic' from Greek 'hygieinós' meaning 'healthy'.

'hygienic' came into English via French 'hygiénique' and Latin/Greek roots (Greek 'hygieinós'); 'antihygienic' was formed in Modern English by adding the prefix 'anti-' to 'hygienic' to express opposition to hygiene.

Literally formed as 'against health' (anti- + hygienic), the word's meaning stabilized to describe things that are unsanitary or likely to cause disease rather than a philosophical opposition to health.