Definition of "moss"

Any of various small, green, seedless plants growing on the ground or on the surfaces of trees, stones, etc.; now specifically, a plant of the phylum Bryophyta (formerly division Musci).  examples

(countable) A kind or species of such plants.  examples

(informal) Any alga, lichen, bryophyte, or other plant of seemingly simple structure.  examples

(now chiefly UK regional) A bog; a fen.  examples

(intransitive) To become covered with moss.  examples

(transitive) To cover (something) with moss.  examples