What is the meaning of Affirm?

To agree, verify or concur; to answer positively.

To assert positively; to tell with confidence; to aver; to maintain as true.

To support or encourage.

To make firm; to confirm, or ratify; especially to assert or confirm, as a judgment, decree, or order, brought before an appellate court for review.

To state under a solemn promise to tell the truth which is considered legally equivalent to an oath, especially of those who have religious or other moral objections to swearing oaths; also solemnly affirm.

Source: wiktionary.org