Vaginal contraction is a contraction

Muscle contraction

Muscle fiber generates tension through the action of actin and myosin cross-bridge cycling. While under tension, the muscle may lengthen, shorten, or remain the same...

 of the pelvic muscles surrounding the vagina

Vagina

The vagina is a fibromuscular tubular tract leading from the uterus to the exterior of the body in female placental mammals and marsupials, or to the cloaca in female birds, monotremes, and some reptiles. Female insects and other invertebrates also have a vagina, which is the terminal part of the...

, which are most commonly associated with sexual intercourse

Sexual intercourse

Sexual intercourse, also known as copulation or coitus, commonly refers to the act in which a male's penis enters a female's vagina for the purposes of sexual pleasure or reproduction. The entities may be of opposite sexes, or they may be hermaphroditic, as is the case with snails...

 and orgasm

Orgasm

Orgasm is the peak of the plateau phase of the sexual response cycle, characterized by an intense sensation of pleasure...

. Although these are generally an involuntary muscular response, some women can control the muscles of the vagina to perform vaginal contractions at will, providing a pleasurable sensation for both parties during sexual intercourse.

Involuntary spasm of the muscles around the vagina, usually caused by anxiety, can result in vaginismus

Vaginismus

Vaginismus, sometimes anglicized vaginism, is the German name for a condition which affects a woman's ability to engage in any form of vaginal penetration, including sexual intercourse, insertion of tampons and/or menstrual cups, and the penetration involved in gynecological examinations...

.

Vaginal contractions should not be confused with uterine contractions.