Jan 6, 2026 foam ˈfōm 1 syllable uncommon ‹ noun. a light frothy mass of fine bubbles formed in or on the surface of a liquid or from a liquid: such as noun. a frothy mass formed in salivating or sweating noun. a stabilized froth produced chemically or mechanically and used especially in fighting oil fires verb. to produce or form foam … streets … foaming with life … verb. to froth at the mouth especially in anger; broadly: to be angry verb. to gush out in foam › Origin Middle English fome, from Old English fām; akin to Old High German feim foam, Latin spuma foam, pumex pumice. Associated Words stuffy