Dihydrotestosterone: A byproduct of the male hormone testosterone. Dihydrotestosterone (DHT) is considered to be the essential androgenic hormone. DHT is responsible for the formation of male primary sex characteristics during embryonic life. It is responsible for the development of most secondary sex characteristics in males at puberty. And it continues to be important to male sexual function throughout adult life. A semisynthetic analog of DHT is called stanolone.