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.

To gather foam; to froth; as, the billows foam.

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.

To cause to foam; as,to foam the goblet; also (with out),
to throw out with rage or violence, as foam.