concatenation vs concatenate

concatenation is a noun but concatenate is not a noun.

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

concatenation (noun)	concatenate (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

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