Confirmer

con·firm  (kn-fûrm)

tr.v. con·firmed, con·firm·ing, con·firms

1. To support or establish the certainty or validity of; verify.

2. To make firmer; strengthen: Working on the campaign confirmed her intention to go into politics.

3. To make valid or binding by a formal or legal act; ratify.

4. To administer the religious rite of confirmation to.

---

[Middle English confirmen, from Old French confermer, from Latin cnfirmre : com-, intensive pref.; see com- + firmre, to strengthen (from firmus, strong; see dher- in Indo-European roots).]

---

con·firma·bili·ty n.

con·firma·ble adj.

con·firma·tory (-fûrm-tôr, -tr) adj.

con·firmer n.

Synonyms: confirm, corroborate, substantiate, authenticate, validate, verify
These verbs mean to affirm the truth, accuracy, or genuineness of something. Confirm implies removal of all doubt: "We must never make experiments to confirm our ideas, but simply to control them" Claude Bernard.
Corroborate refers to supporting something by means of strengthening evidence: The witness is expected to corroborate the plaintiff's testimony.
To substantiate is to establish by presenting substantial or tangible evidence: "one of the most fully substantiated of historical facts" James Harvey Robinson.
Authenticate implies the establishment of genuineness of something by the testimony of an expert: Never purchase an antique before it has been authenticated.
Validate refers to establishing the validity of something, such as a theory, claim, or judgment: The divorce validated my parents' original objection to the marriage.
Verify implies proving by comparison with an original or with established fact: The bank refused to cash the check until the signature was verified.