A French kiss (or tongue kiss) is a romantic or sexual kiss in which one participant's tongue touches the other's lips or tongue and may enter their mouth.

While family members may sometimes kiss on the lips, a tongue kiss almost always indicates a romantic or sexual relationship. French kissing stimulates the lips, tongue and mouth, which are all areas very sensitive to touch. It is considered by many to be both very pleasurable and highly intimate.

In a tongue kiss participants may exchange saliva, which would often be considered disgusting in other contexts, but which may add to the passion and excitement of the sexual kiss. Although most sexually-transmitted diseases are not transmitted by kissing, the exchange of saliva in a French kiss may increase the chances of catching an orally transmitted disease.

Although popular in the west, it's catching up fast in the east. French kiss is commonly used in movies to show willing sex between lovers. It is often used by lovers to express their intimate feeling toward each other and more often precedes sex.

French kissing is sometimes referred to in literature as a soul kiss or a columbine kiss (columbine meaning like doves). It is known colloquially as tongue wrestling, tonsil hockey and, in the United Kingdom, snogging.

Unlike other English terms using the adjective "French", the expression has been borrowed into colloquial French as the verb frencher. The term has been attributed to the French's more open views on cunnilingus and oral sex in general (see soixante-neuf/sixty-nine), as the two acts are similar.

Asymmetry in kissing

In order to avoid clashing noses, a couple will often turn their heads to one side or another when kissing, so that they're heads are at an angle from one another. Often, to make this more comfortable, one person, sitting upright, will support another, perhaps across their lap and in their arms, thus combining hugging and kissing. The person supporting the other is most likely taking the more active role in kissing the other. Writing in Nature, psychologist Oner Güntürkün observed couples kissing in public places such as airports and parks, and showed that the direction of turning is more frequently to the right than the left by a 2:1 ratio. Güntürkün ascribed this asymmetry to a neonatal right side preference.

(data from Nature 421, 711 (13 February 2003); doi:10.1038/421711a)

Maraichinage

A possible predecessor of the term tongue kiss is the Maraichinage, popularised by the residents of Pays de Mont in Brittany: the Maraichins. A maraichinage often lasted for several hours, and involved a profound exploration of the mouth of one's partner.

French Kiss is a 1995 movie starring Meg Ryan and Kevin Kline.

Deep Kiss is a series of Japanese pornographic lesbian movies, dedicated entirely to French kissing.