concatenate vs concatenation

concatenate is not a noun while concatenation is a noun.

Word	Noun	Adjective	Verb	Adverb
concatenate	No	No	Yes	No
concatenation	Yes	No	No	No

concatenate (noun)	concatenation (noun)
	the act of linking together as in a series or chain
	a series of things depending on each other as if linked together
	the linking together of a consecutive series of symbols or events or ideas etc
	the state of being linked together as in a chain; union in a linked series

concatenate (verb)	concatenation (verb)
add by linking or joining so as to form a chain or series
combine two strings to form a single one