Webster's Revised Unabridged Dictionary · 1913

Foam

Foam (fōm) , noun

[Old English fam, fom, Anglo-Saxon fām; akin to Old High German & German feim.]

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.
Collocations (1)
Foam cock , in steam boilers, a cock at the water level, to blow off impurities.

Foam (fōm) , intransitive verb

[Anglo-Saxon faman. See Foam, n.]

1.
To gather foam; to froth; as, the billows foam.
He foameth, and gnasheth with his teeth. — Mark ix. 18
2.
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.

Foam (fōm) , transitive verb

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