出典:Wikipedia
出典:『Wikipedia』 (2011/07/29 16:32 UTC 版)
Sexual intercourse, also known as copulation or coitus, commonly refers to the act in which a male's penis penetrates a female's vagina for the purposes of sexual pleasure or reproduction. The sex partners may be of opposite sexes, or they may be hermaphroditic, as is the case with snails. The definition may also include other penetrative sexual acts, such as oral sex, anal sex and fingering, which can be practiced by both heterosexual and same-sex partners.