populate vs population

populate is not a noun while population is a noun.

Word	Noun	Adjective	Verb	Adverb
populate	No	No	Yes	No
population	Yes	No	No	No

populate (noun)	population (noun)
	the act of populating (causing to live in a place)
	(statistics) the entire aggregation of items from which samples can be drawn
	the people who inhabit a territory or state
	a group of organisms of the same species inhabiting a given area
	the number of inhabitants (either the total number or the number of a particular race or class) in a given place (country or city etc.)

populate (verb)	population (verb)
fill with inhabitants
be an inhabitant of or reside in