baseball bat vs lumber

baseball bat and lumber both are nouns.

Word	Noun	Adjective	Verb	Adverb
baseball bat	Yes	No	No	No
lumber	Yes	No	Yes	No

As nouns, baseball bat and lumber are synonyms defined as:

baseball bat (noun)	lumber (noun)
an implement used in baseball by the batter	an implement used in baseball by the batter
	the wood of trees cut and prepared for use as building material

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