foam
n 1: a mass of small bubbles formed in or on a liquid [syn: {froth}]
2: a lightweight material in cellular form; made by introducing
gas bubbles during manufacture
v 1: of liquids; "The boiling soup was frothing" [syn: {froth}, {fizz},
{effervesce}, {sparkle}]
2: foam as if boiling; "a seething liquid" [syn: {seethe}]
3: make froth, become bubbly; "The river foamed" [syn: {froth},
{spume}, {suds}]