noun

a mass of small bubbles in liquid caused by agitation, fermentation, or salivating.

leave the yeast until there is a good head of froth

foam,lather,head,suds,bubbles,frothiness,fizz,effervescence,mousse,scum,spume

verb

form or contain a rising or overflowing mass of small bubbles.

the red blood frothed at his lips

bubble,fizz,foam,cream,lather,effervesce,aerate,churn,seethe,roil,spume