confirm

Concise Oxford English Dictionary © 2008 Oxford University Press:
confirm/kənˈfɜːm/

▶verb

• 1 establish the truth or correctness of.

  ■ state with assurance that something is true.

  ■ (confirm someone in) reinforce someone in (an opinion or feeling).

• 2 make (a provisional arrangement) definite.

  ■ formally declare that (someone) is appointed to a post.

• 3 administer the religious rite of confirmation to.

– derivatives
confirmative adjective,
confirmatory adjective.

– origin ME: from OFr. confermer, from L. confirmare, from con- ‘together’ + firmare ‘strengthen’ (from firmus ‘firm’).