A person who acknowledges or recognizes something. As an acknowledger of his team's hard work, the manager made sure to thank everyone during the meeting.
A person who gives recognition or expresses gratitude. The acknowledger of the award took the stage to express her appreciation for the support she received.
In law, a person who formally acknowledges a deed, fine, or other legal instrument before a court or authorized officer. The acknowledger appeared before the registrar to confirm that he had signed the deed of conveyance.