Laç

The suffix -lock in Modern English survives only in . 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.

The Old English nouns in -lác include brýdlác "nuptials", beadolác, feohtlác and heaðolác "warfare", hǽmedlác and wiflác "sexual intercourse", réaflác "robbery", wítelác "punishment", wróhtlác "calumny" besides the wedlác "pledge-giving", also "nuptials" ancestral to wedlock. A few compounds appear only in Middle English, thus dweomerlak "occult practice, magic", ferlac "terror", shendlac "disgrace", treulac "faithfulness", wohlac "wooing", all of them extinct by the onset of Early Modern English. The earliest words taking the -lác suffix were probably related to warfare, comparable to the -pleȝa () suffix found in "swordplay".

The Old Norse counterpart is -leikr, loaned into North Midlands Middle English as , in the Ormulum appearing as -leȝȝe. The suffix came to be used synonymously with -nesse, forming abstract nouns, e.g. clænleȝȝe "cleanness".

The etymology of the suffix is the same as that of the noun lác 'play, sport,' but also 'sacrifice, offering,' corresponding to obsolete Modern English lake (dialectal laik) 'sport, fun, glee, game,' cognate to Gothic laiks 'dance,' Old Norse leikr 'game, sport' (origin of English lark 'play, joke, folly') and Old High German leih 'play, song, melody.' Ultimately, the word descends from Proto-Germanic *laikaz. Old English lícian ('to please,' Modern English ) is from the same root. In modern English, the noun has been reintroduced through the cognate Swedish lek as a specialist term referring to mating behavior.

...
Wikipedia