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.
Origin: AS. F?man. See Foam, n.
Source: Websters Vocabulary