Confirm
Confirm (verb) /kənˈfɜːm/ US /-ˈfɝːm/
to prove that something is true, verify, make certain, reinforce, strengthen, corroborate, check, substantiate, prove, bear out, validate
Her pale complexion confirmed that she’d been scared to death.
Antonyms: refute, weaken
Noun: confirmation
Noun: confirmer
Adjective: confirmable
Adjective: confirmatory