Sexually transmitted disease (STD): A disease passed from one person to another by unprotected sexual contact. You can get a sexually transmitted disease from sexual activity that involves the mouth, anus, penis, or vagina.
Sexual masochism: A disorder in which a person uses sexual fantasies, urges, or behaviors involving the act (real, not simulated) of being humiliated, beaten, or otherwise made to suffer in order to achieve sexual excitement and climax.
Sexual orientation: A term used to refer to a person's emotional, romantic, and sexual attraction to individuals of a particular gender (male or female).
Sexual response cycle: The sequence of physical and emotional changes that occur as a person becomes sexually aroused and participates in sexually stimulating activities, including intercourse and masturbation. The sexual response cycle has four phases: excitement, plateau, orgasm, and resolution.
Sexual sadism: A disorder in which a person has persistent fantasies in which sexual excitement results from inflicting psychological or physical suffering (including humiliation and terror) on a sexual partner.
Simple vulvectomy: A procedure that removes the entire vulva but no lymph nodes.
Skinning vulvectomy: A procedure to remove only the skin of the vulva that contains cancer.
Smegma: A thick, bad-smelling substance that results when oily secretions from the skin accumulate under the foreskin of the penis.
Sonogram (ultrasound): The use of sound waves to form an image of internal organs.
Speculum: An instrument inserted into the vagina to allow the doctor to view the inside of the vagina.
Sperm: The male reproductive cells.
Spermicide: Foams, jellies, tablets, or suppositories that a woman places in her vagina and up next to the cervix (the opening leading from the vagina to the womb) before sex to prevent pregnancy. Spermicides block the cervix and paralyze the sperm, making them unable to travel into the womb.
Spermatic cord: The structure that secures the testicles within the scrotum.
Spermatogenesis: The process of producing sperm, the male reproductive cells.
Squamous cells: The thin, flat cells that line the surface of many organs of the body.
Squamous cell carcinomas: Cancer that begins in the squamous cells.