'antifoam' originates from the combining prefix 'anti-' (from Greek 'anti' meaning 'against') and the English word 'foam'.

'antifoam' was formed in modern English by combining 'anti-' + 'foam'; the -ing form 'antifoaming' developed as a present participle/adjectival form and as a noun (gerund). 'Foam' itself comes from Old English 'fām' (Middle English 'foam').

Initially formed to mean 'against foam' in a literal compositional sense; over time it came to be used specifically for substances or actions that prevent or reduce foam and for adjectival use (e.g., 'antifoaming agent').