validate vs cosign

validate and cosign both are verbs.

Word	Noun	Adjective	Verb	Adverb
validate	No	No	Yes	No
cosign	No	No	Yes	No

As verbs, cosign is a hyponym of validate; that is, cosign is a word with a more specific, narrower meaning than validate:

Other hyponyms of validate include ratify, sign, co-sign, probate.

validate (verb)	cosign (verb)
make valid or confirm the validity of	sign and endorse (another person's signature), as for a loan
prove valid; show or confirm the validity of something	sign jointly
give evidence for
declare or make legally valid