noun

a mass of small bubbles formed on or in liquid, typically by agitation or fermentation.

a beer with a thick head of foam

froth,spume,surf,spindrift,spray,fizz,effervescence,mousse,bubbles,head,lather,suds

verb

form or produce a mass of small bubbles; froth.

the sea foamed beneath them

froth,froth up,cream,bubble,fizz,effervesce,spume,lather,ferment,rise,boil,seethe,simmer