learn vs witness

learn is not a noun while witness is a noun.

Word	Noun	Adjective	Verb	Adverb
learn	No	No	Yes	No
witness	Yes	No	Yes	No

learn (noun)	witness (noun)
	testimony by word or deed to your religious faith
	someone who sees an event and reports what happened
	a close observer; someone who looks at something (such as an exhibition of some kind)
	(law) a person who attests to the genuineness of a document or signature by adding their own signature
	(law) a person who testifies under oath in a court of law

learn (verb)	witness (verb)
gain knowledge or skills	be a witness to
get to know or become aware of, usually accidentally	perceive or be contemporaneous with
be a student of a certain subject
commit to memory; learn by heart
impart skills or knowledge to
find out, learn, or determine with certainty, usually by making an inquiry or other effort