foam (n.) Look up foam at Dictionary.com
Old English fam "foam, saliva froth," from West Germanic *faimo- (cognates: Old High German veim, German Feim), from PIE *(s)poi-mo-, a root with connotations of "foam, froth" (cognates: Sanskrit phenah; Latin pumex "pumice," spuma "foam;" Old Church Slavonic pena "foam;" Lithuanian spaine "a streak of foam"). The rubber or plastic variety so called from 1937.
foam (v.) Look up foam at Dictionary.com
Old English famgian "to foam," from the source of foam (n.). Related: Foamed; foaming.