corroborate vs corroboratory

corroborate is not an adjective while corroboratory is an adjective.

Word	Noun	Adjective	Verb	Adverb
corroborate	No	No	Yes	No
corroboratory	No	Yes	No	No

corroborate (adjective)	corroboratory (adjective)
	serving to support or corroborate

corroborate (verb)	corroboratory (verb)
establish or strengthen as with new evidence or facts
give evidence for
support with evidence or authority or make more certain or confirm