'antihormone' is formed in modern English from the combining prefix 'anti-' (from Greek 'anti-' meaning 'against') + 'hormone' (from Greek 'hormōn', from 'hormāein' meaning 'to set in motion' or 'to excite').

'hormone' was coined in the early 20th century (from Greek roots) and 'antihormone' was later formed by attaching the prefix 'anti-' to describe substances acting against hormones; the word entered medical usage in the 20th century as treatments targeting hormonal action were developed.

Initially the elements meant 'against' + 'that which sets in motion'; over time the compound came to mean specifically 'a substance that blocks or counteracts a hormone' in medical contexts.