APA Dictionary of Psychology

a medically supervised treatment in which hormones and related medications are prescribed to transgender, nonbinary, or gender-diverse individuals to bring their physical characteristics into closer alignment with their gender identity. It typically involves the administration of sex steroids (such as estrogen or testosterone) and, when appropriate, hormone blockers, such as gonadotropin releasing hormone analogues (GnRHa), or antiandrogens to adjust secondary sex characteristics (e.g., body hair, fat distribution, breast growth, or voice change) in a way that reflects the person’s affirmed gender. Gender-affirming hormone therapy can be a component of gender-affirming care, and emphasizes informed consent, assessment of gender dysphoria or incongruence, and regular health monitoring throughout treatment.