This paper constructs a brief history of the biochemical term agonist by exploring the multiple meanings of the root ag�n in ancient Greek literature and describing how agonist first appeared in the scientific literature of the 20th century in the context of neurophysiologists' debates about the existence and properties of cellular receptors. While the narrow scientific definition of agonist may appear colorless and dead when compared with the web of allusions spun by the ancient Greek ag�n, the scientific power and creativity of agonist actually resides precisely in its exact, restricted meaning for biomedical researchers.