Erotic arousal

Sexual arousal (also sexual excitement) is the arousal of sexual desire, during or in anticipation of sexual activity. A number of physiological responses occur in the body and mind as preparation for sexual intercourse and continue during it. Genital responses are not the only changes, but noticeable and necessary for consensual and comfortable intercourse. Male arousal will lead to an erection, and in female arousal the body's response is engorged sexual tissues such as nipples, vulva, clitoris, vaginal walls and vaginal lubrication. Mental stimuli and physical stimuli such as touch, and the internal fluctuation of hormones, can influence sexual arousal.

Sexual arousal has several stages and may not lead to any actual sexual activity, beyond a mental arousal and the physiological changes that accompany it. Given sufficient sexual stimulation, sexual arousal in humans reaches its climax during an orgasm. It may also be pursued for its own sake, even in the absence of an orgasm.

There are several informalities, terms and phrases to describe sexual arousal including horny,turned on, randy, steamy, and lustful. Things that precipitate human sexual arousal are called erotic stimuli and colloquially known as turn-ons.

Depending on the situation, a person can be sexually aroused by a variety of factors, both physical and mental. A person may be sexually aroused by another person or by particular aspects of that person, or by a non-human object. The welcome physical stimulation of an erogenous zone or acts of foreplay can result in arousal, especially if it is accompanied with the anticipation of imminent sexual activity. Sexual arousal may be assisted by a romantic setting, music or other soothing situation. The potential stimuli for sexual arousal vary from person to person, and from one time to another, as does the level of arousal.

...
Wikipedia