froth n.

c. 1300, from an unrecorded Old English word, or else from Old Norse froða "froth," from Proto-Germanic *freuth- "froth" (source also of Swedish fradga, Danish fraade). Old English had afreoðan "to froth," from the same root. The modern verb is late 14c., from the noun. Related: Frothed; frothing.