Foam \Foam\, v.i. [imp. & p. p. Foamed; p. pr. & vb. n. Foaming.]

[AS. f?man. 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.

Source: Webster's Revised Unabridged Dictionary (1913)