The noun affirmation means a statement that something is correct or accurate.

Synonyms are confirmation, assertion, attestation, or avowal.

The word origins from Old French (14th century) afermacion meaning “confirmation” and Latin affirmationem meaning “an affirmation, solid assurance”, noun of action from past-participle stem of affirmare meaning “to make steady, strengthen, confirm”. It comes from ad meaning “to” plus firmare meaning “strengthen, make firm”, from firmus meaning “strong”.

I really need the chairman’s affirmation to be able to proceed.

Nodding is a sign of affirmation.

His affirmation impacts the whole group.