'antidepressant' originates from English, specifically from the combining of the prefix 'anti-' (from Greek, meaning 'against') and 'depressant' (from 'depress' + '-ant'), where 'anti-' meant 'against' and 'depress' derived from Latin elements meaning 'to press down'.

'antidepressant' was formed in modern English in the 20th century by adding the prefix 'anti-' to the existing word 'depressant'; 'depressant' itself developed from Middle English/Modern English 'depress' which comes from Old French and Latin 'deprimere' and eventually became the English 'depress' and then 'depressant'.

Initially, Latin 'deprimere' meant 'to press down'; over time this gave rise to English 'depress' meaning 'to lower in mood or position', and 'antidepressant' evolved to mean 'a substance that counteracts or prevents depression' rather than any physical pressing action.