Agonist, LHRH: A compound that is similar to LHRH (luteinizing hormone-releasing hormone) in structure and is able to it performs its action(s). Luteinizing hormone-releasing hormone is a naturally occurring hormone that controls sex hormones in both men and women. Thus, an LHRH agonist serves in a manner similar to LHRH to control the same sex hormones.

An agonist achieves a normal action, often mimicking the action of a naturally occurring substance. The word "agonist" comes from the Late Latin agnista, contender, from the Greek agnists, contestant, from agn, contest. An agonist is a chemical contestant.