'antihypochondriac' is formed from the prefix 'anti-' (from Greek 'anti', meaning 'against') + 'hypochondriac' (from Greek 'hypokhondrios'), literally 'under the cartilage/rib area'.

'hypochondriac' comes from Greek 'hypokhondrios' ('hypo-' meaning 'under' + 'khondros' meaning 'cartilage'), passed into Latin as 'hypochondriacus' and into Middle English via Old French; 'anti-' (Greek) was later prefixed in Modern English to create 'antihypochondriac.'

Originally related to the bodily region 'under the ribs' and associated melancholic humours, 'hypochondriac' evolved to mean excessive health anxiety; 'antihypochondriac' thus developed to denote opposition to or alleviation of that condition.