dam up vs dam

dam up is not a noun while dam is a noun.

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

As verbs, dam up and dam are synonyms defined as:

dam up (noun)	dam (noun)
	female parent of an animal especially domestic livestock
	a barrier constructed to contain the flow of water or to keep out the sea
	a metric unit of length equal to ten meters

dam up (verb)	dam (verb)
obstruct with, or as if with, a dam	obstruct with, or as if with, a dam