Old English cyssan "to touch with the lips" (in respect, reverence, etc.), from Proto-Germanic *kussjan (source also of Old Saxon kussian, Old Norse kyssa, Old Frisian kessa, Middle Dutch cussen, Dutch, Old High German kussen, German küssen, Norwegian and Danish kysse, Swedish kyssa), from *kuss-, probably ultimately imitative of the sound. Gothic used kukjan. Of two persons, "to reciprocally kiss, to kiss each other," c. 1300. Related: Kissed; kissing. The vowel was uncertain through Middle English; for vowel evolution, see bury.
Kissing, as an expression of affection or love, is unknown among many races, and in the history of mankind seems to be a late substitute for the more primitive rubbing of noses, sniffing, and licking. [Carl Darling Buck, "A Dictionary of Selected Synonyms in the Principal Indo-European Languages," 1949, p.1113]
There appears to be no common Indo-European root word for "kiss," though suggestions of a common ku- sound may be found in the Germanic root and Greek kynein "to kiss," Hittite kuwash-anzi "they kiss," Sanskrit cumbati "he kisses." Some languages make a distinction between the kiss of affection and that of erotic love (compare Latin saviari "erotic kiss," vs. osculum, literally "little mouth"). French embrasser "kiss," but literally "embrace," came about in 17c. when the older word baiser (from Latin basiare) acquired an obscene connotation.
To kiss the cup "drink liquor" is early 15c. To kiss the dust "die" is from 1835. To kiss and tell is from 1690s. Figurative (and often ironic) kiss (something) goodbye is from 1935. To kiss (someone) off "dismiss, get rid of" is from 1935, originally of the opposite sex. Insulting invitation kiss my arse (or ass) as an expression of contemptuous rejection is from at least 1705, but probably much older (see "The Miller's Tale").