The Collaborative International Dictionary of English v.0.48:

Foam \Foam\ (f[=o]m), v. i. [imp. & p. p. Foamed (f[=o]md); p.
   pr. & vb. n. Foaming.] [AS. f[=ae]man. See Foam, n.]
   1. To gather foam; to froth; as, the billows foam.
      [1913 Webster]

            He foameth, and gnasheth with his teeth. --Mark ix.
                                                  18.
      [1913 Webster]

   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.
      [1913 Webster]