pick up vs witness

pick up is not a noun while witness is a noun.

Word	Noun	Adjective	Verb	Adverb
pick up	No	No	Yes	No
witness	Yes	No	Yes	No

pick up (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

pick up (verb)	witness (verb)
gain or regain energy	be a witness to
improve significantly; go from bad to good	perceive or be contemporaneous with
lift out or reflect from a background
get to know or become aware of, usually accidentally
eat by pecking at, like a bird
take into custody
take up by hand
fill with high spirits; fill with optimism
give a passenger or a hitchhiker a lift
take and lift upward
perceive with the senses quickly, suddenly, or momentarily
register (perceptual input)
buy casually or spontaneously
gather or collect
get in addition, as an increase
meet someone for sexual purposes