An extract made from the fruit of the chaste tree (Vitex agnus-castus) found in parts of Asia and Europe. It is claimed to treat infertility and to lessen symptoms that may occur before or during a woman’s menstrual period, such as headaches and irregular bleeding. Monk’s pepper may affect levels of reproductive hormones in the blood. It is a type of phytomedicine. Also called chaste tree berry and Vitex.