What is "-lock"

The suffix -lock in Modern English survives only in wedlock. It descends from Old English -lác which was more productive, carrying a meaning of "action or proceeding, state of being, practice, ritual". As a noun, Old English lác means "play, sport", deriving from an earlier meaning of "sacrificial ritual or hymn" (Proto-Germanic *laikaz). A putative term for a "hymn to the gods" (* ansu-laikaz) in early Germanic paganism is attested only as a personal name, Oslac.