'anti-cachectic' originates from Greek-derived elements: the prefix 'anti-' (from Greek 'anti-' meaning 'against') combined with 'cachectic' (from 'cachexia'). 'cachexia' itself comes from Greek 'kakēxia', where 'kak-' meant 'bad' and 'hexis' meant 'condition'.

'cachexia' entered English via New Latin/medical Latin from Greek 'kakēxia'; the adjective 'cachectic' was formed in English from that noun, and the compound 'anti-cachectic' (literally 'against cachexia') arose in modern medical English (20th century onward) to describe agents or effects that counteract wasting.

Initially the elements meant 'against' + 'bad condition'; over time the compound has come to be used specifically to mean 'counteracting or preventing cachexia (wasting),' especially in medical contexts.