The following glossary is adapted from the glossary provided by Planned Parenthood at https://www.plannedparenthood.org/learn/glossary.
Scabies: Tiny mites that can be sexually transmitted. They burrow under the skin, causing intense itching, usually at night, and small bumps or rashes that appear in dirty-looking, small curling lines, especially on the penis, between the fingers, on buttocks, breasts, wrists, and thighs, and around the navel.
Scrotum: A sac of skin, divided into two parts, enclosing the testes, epididymides, and parts of the vasa deferentia.
Secondary sex characteristics: Features of the body that are caused by hormones, develop during puberty, and last through adult life. For women, these include breast development and widened hips. For men, they include facial hair development. Both genders develop pubic hair and underarm hair.
Secondary syphilis: The second stage of the infection, during which a rash and fever develop.
Semen: Fluid containing sperm that is ejaculated during sexual excitement. Semen is composed of fluid from the seminal vesicles, fluid from the prostate, and sperm from the testes.
Seminal fluid: A fluid that nourishes and helps sperm to move. Made in the seminal vesicles.
Seminal vesicle: One of two small organs located beneath the bladder and connected to the urethra that produce seminal fluid.
Seminiferous tubules: A network of tiny tubules in the testes that constantly produce sperm. Seminiferous tubules also produce androgens, the “male” sex hormones.
Sex cell: A reproductive cell. See gamete.
Sexually transmitted disease or STD: A sexually transmitted infection that has developed symptoms. Used interchangeably with “sexually transmitted infection.
Sexually transmitted infection or STI: An STD that has not (yet) caused disease symptoms.
Skene’s glands: Two glands that gush fluid during female ejaculation. They are located on opposite sides of the opening to a woman’s urethra. Also called paraurethral glands or female prostate glands.
Smegma: A sticky, white, unpleasant-smelling substance produced under the foreskin at the glans of the penis and clitoris. It is formed by secretions from the Tyson’s glands, bacteria, and body oils.
Somatotropin: The human growth hormone secreted by the pituitary gland.
Sperm: The reproductive cells in men, produced in the seminiferous tubules of the testes.
Spermarche: The time when sperm is first produced by the testes of a boy.
Spermatogenesis: The process of producing sperm. Occurs in the seminiferous tubules of the testes.
Spermicides: Chemicals used to immobilize and kill sperm.
Spirochete: The organism that causes syphilis.
Spotting: Usually, light bleeding between menstrual periods, which may only be seen on toilet tissue after wiping. Normal spotting is associated, for example, with ovulation, the use of some hormonal methods of birth control, the onset of menstruation, and perimenopause. Though not always abnormal, spotting during pregnancy or after vaginal intercourse should be discussed with one’s health care provider. It can be a sign of endometriosis, uterine fibroids, vaginal adhesions or polyps, or cancer.
Standard days method: A fertility awareness-based method for predicting a woman’s fertility by tracking her cycle on a string of CycleBeads. Can be used for contraception by women whose cycles are no shorter than 26 days or longer than 32 days.
STD: See sexually transmitted disease.
Sterilization: Surgical methods of birth control that are intended to be permanent—blocking of the fallopian tubes for women or the vas deferens for men.
STI: See sexually transmitted disease.
Syphilis: A sexually transmitted infection that can lead to disfigurement, neurological disorders, and death.
Semen: Liquid containing sperm produced on ejaculation.