think up vs think

think up is not a noun while think is a noun.

Word	Noun	Adjective	Verb	Adverb
think up	No	No	Yes	No
think	Yes	No	Yes	No

think up (noun)	think (noun)
	an instance of deliberate thinking

think up (verb)	think (verb)
devise or invent	bring into a given condition by mental preoccupation
	use or exercise the mind or one's power of reason in order to make inferences, decisions, or arrive at a solution or judgments
	judge or regard; look upon; judge
	recall knowledge from memory; have a recollection
	expect, believe, or suppose
	have in mind as a purpose
	be capable of conscious thought
	focus one's attention on a certain state
	decide by pondering, reasoning, or reflecting
	ponder; reflect on, or reason about
	have or formulate in the mind
	dispose the mind in a certain way
	imagine or visualize