certify

Short definition from Wiktionary

Verb

1. 1
   To attest to (a fact) as the truth.
2. 2
   To authenticate or verify in writing.
3. 3
   To attest that a product, service, organization, or person has met an official standard.
4. 4
   To inform; to tell (a person) that something is true.
5. 5
   To assure (oneself) of something; to ascertain.