'Peat moss' definitions:

Definition of 'peat moss'

noun

Any of various pale or ashy mosses of the genus Sphagnum whose decomposed remains form peat [syn: sphagnum, sphagnum moss, peat moss, bog moss]

From: GCIDE

Peat \Peat\, n. [Prob. for beat, prop., material used to make the fire burn better, fr. AS. b[=e]tan to better, mend (a fire), b[=o]t advantage. See Better, Boot advantage.] A substance of vegetable origin, consisting of roots and fibers, moss, etc., in various stages of decomposition, and found, as a kind of turf or bog, usually in low situations, where it is always more or less saturated with water. It is often dried and used for fuel. [1913 Webster]
Peat bog, a bog containing peat; also, peat as it occurs in such places; peat moss.
Peat moss. (a) The plants which, when decomposed, become peat. (b) A fen producing peat. (c) (Bot.) Moss of the genus Sphagnum, which often grows abundantly in boggy or peaty places.
Peat reek, the reek or smoke of peat; hence, also, the peculiar flavor given to whisky by being distilled with peat as fuel. [Scot.] [1913 Webster]