"foam" in the noun sense
1. foam, froth
a mass of small bubbles formed in or on a liquid
"the beer had a thick head of foam"
a lightweight material in cellular form made by introducing gas bubbles during manufacture
"foam" in the verb sense
1. foam, froth, fizz, effervesce, sparkle, form bubbles
become bubbly or frothy or foaming
"The boiling soup was frothing"
"The river was foaming"
Source: WordNet® (An amazing lexical database of English)
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