foam (
http://definr.com/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]