'antifoam' originates from Modern English, specifically formed from the prefix 'anti-' and the noun 'foam'; 'anti-' ultimately traces to Greek 'anti' meaning 'against', and 'foam' traces to Old English 'fām'/'fōm' meaning 'foam'.

'antifoam' is a relatively modern compound word formed by joining 'anti-' + 'foam' (reflecting 20th-century development of industrial chemical additives); there is no direct medieval compound predecessor—rather the components 'anti-' and 'foam' were joined in modern usage.

Initially the elements together simply meant 'against foam'; over time the compound came to be used as a noun referring specifically to a substance or agent used to prevent or reduce foam in processes.