Other forms: foams
Foam is the white mass of tiny bubbles that forms on top of waves or liquid. Sea foam, a head of foam, the foam on the beer.
It also names the soft solid material made by trapping bubbles in plastic or rubber: foam mattress, foam padding, memory foam. Firefighting foam smothers a fire by cutting off its air. As a verb, foam means to produce it, and foam at the mouth means either the literal symptom or, figuratively, to be in a rage. Note foamy, the adjective, and shaving foam.
1nounfoamA white mass of tiny bubbles on liquid.
“There was a line of foam along the whole tideline.”
2nounsoftA soft material made by trapping bubbles in plastic.
“The foam in the seat gave up years ago.”
foam is a mass of bubbles.
Old English fam descends from a Proto-Indo-European root that also gives Latin spuma, foam, and pumex — the source of pumice, a rock made of frozen bubbles.
Proto-Indo-European
*(s)poH(y)-
Proto-Indo-European
*(s)poHy-m-os
Proto-Germanic
*faimaz
Proto-West Germanic
*faim
Old English
fām
Middle English
fom
English, today
foam
Built from
From Middle English fom, foom, from Old English fām, from Proto-West Germanic faim, from Proto-Germanic faimaz, from Proto-Indo-European (s)poHy-m-os, from (s)poH(y)- (“foam”). Cognate with German Feim (“foam”), Latin spūma (“foam”), Latin pūmex (“pumice”), Sanskrit फेन (“foam”), possibly kmr fê (“epilepsy”).
Etymology from Wiktionary, CC BY-SA