foam

nouns

a mass of small bubbles formed in or on a liquid

"the beer had a thick head of foam"

foam, froth

is derived from

a lightweight material in cellular form; made by introducing gas bubbles during manufacture

foam

is a type of (narrower)

the tangible substance that goes into the makeup of a physical object

"coal is a hard black material"; "wheat is the stuff they use to make bread"

become bubbly or frothy or foaming

"The boiling soup was frothing"; "The river was foaming"; "Sparkling water"

effervesce, fizz, foam, form bubbles, froth, sparkle