Imperforate hymen

A condition where the hymen is unperforated making bloodflow or penetration impossible.  Can be easily corrected with surgery.  

Impotence

The inability to achieve and maintain an erection.  Causes could be physical, psychological, drug induced or old age. 

Impregnate

To make pregnant.

Incest

Sexual activity between relatives or family members. 

Infatuation

An intense but temporary obsession over someone; irrational, superficial and short lived. 

Inhibited orgasm

Consistent difficulty or inability to reach orgasm.  Also referred to as ejaculatory incompetence or retarded ejaculation.

Inhibited sexual desire

A sexual disorder characterized by low or no sexual desire.  

Inner lips

The folds of skin on either side of the vaginal entrance, between the outer lips, that enclose the clitoris and the vaginal opening. Also known as labia minora.

Intercourse

Sexual activity in which the penis is inserted into the vagina or anus. 

Interfemoral intercourse

Sexual activity in which the penis is thrust between the thighs of a partner.  

Internalized homophobia

Hatred of oneself due to homosexual orientation.

Interstitial cells

Cells in the testes that secrete male sex hormones; also known as Leydig cells.

Intrauterine Device (IUD)

A plastic or metal device that is inserted into the uterus by a physician to prevent pregnancy. Remains in place for two to five years.

Introitus

The opening to the vagina.

Intromission

Insertion of the penis into the vagina.

Inverted nipple