sex drive
an arousal state precipitating the desire for sexual gratification and, usually, for sexual reproduction. Although it is not necessary for an individual’s survival, it is considered a primary drive because it is essential for species survival. In many animals, sexual activity is cyclical (e.g., seasonal or dependent on cyclical hormone release), although a variety of factors (e.g., external stimulation) may arouse the drive. Also called sexual drive. See libido.