Endorsement

Definition
An endorsement means "any advertising message (including verbal statements, demonstrations, or depictions of the name, signature, likeness or other identifying personal characteristics of an individual or the name or seal of an organization) that consumers are likely to believe reflects the opinions, beliefs, findings, or experiences of a party other than the sponsoring advertiser, even if the views expressed by that party are identical to those of the sponsoring advertiser."

Source
Federal Trade Comm’n, Guides Concerning the Use of Endorsements and Testimonials in Advertising 56 (Dec. 1, 2009).