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English definition of “foam”

foam

noun [U]  /foʊm/ us  
a mass of small, usually white, bubbles formed on the surface of a liquid: The waves were high and capped with foam. Foam is also a type of light material made by adding gas bubbles to a liquid, then letting it cool, used esp. in packaging.

foam

verb [I]  /foʊm/ us  
to produce a mass of small bubbles: The suds in the sink foamed up when she added hot water.
(Definition of foam from the Cambridge Academic Content Dictionary © Cambridge University Press)
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