timber vs lumber

timber and lumber both are nouns.

Word	Noun	Adjective	Verb	Adverb
timber	Yes	No	No	No
lumber	Yes	No	Yes	No

As nouns, timber and lumber are synonyms defined as:

timber and lumber: the wood of trees cut and prepared for use as building material

timber (noun)	lumber (noun)
a beam made of wood	an implement used in baseball by the batter
a post made of wood	the wood of trees cut and prepared for use as building material
(music) the distinctive property of a complex sound (a voice or noise or musical sound)
land that is covered with trees and shrubs
the wood of trees cut and prepared for use as building material

timber (verb)	lumber (verb)
	cut lumber, as in woods and forests
	move heavily or clumsily