·noun To gather foam; to Froth; as, the billows foam.
II. Foam (·vt) To cause to foam; as,to foam the goblet; also (with out), to throw out with rage or violence, as foam.
III. Foam ·noun To form foam, or become filled with foam;
— said of a steam boiler when the water is unduly agitated and frothy, as because of chemical action.
IV. Foam ·noun The white substance, consisting of an aggregation of bubbles, which is formed on the surface of liquids, or in the mouth of an animal, by violent agitation or fermentation; froth; spume; scum; as, the foam of the sea.