luck

From Middle English luk, lukke, related to Old Frisian luk (“luck”), West Frisian gelok (“luck”), Saterland Frisian Gluk (“luck”), Dutch geluk (“luck, happiness”), Low German luk (“luck”), German Glück (“luck, good fortune, happiness”), Danish lykke (“luck”), Swedish lycka (“luck”), Icelandic lukka (“luck”). According to the OED, it may be related to lock. A loanword into English in the 15th century (probably as a gambling term) from Middle Dutch luc, a shortened form of gheluc (“good fortune”), whence Modern Dutch geluk. Middle Dutch luc, gheluc has parallels with Middle High German lücke, gelücke (Modern German Glück). The word occurs only from the 12th century, apparently first in Rhine Frankish. Perhaps from a Frankish *galukki. The word enters standard Middle High German during the 13th century, and spreads to English and Scandinavian in the Late Middle Ages. Its origin seems to have been regional or dialectal, and there were competing German words such as gevelle or schick, or the Latinate fortūne from Latin fortūna. Its etymology is unknown, although there are numerous proposals as to its derivations from a number of roots. Use as a verb in American English is late (1940s), but there was a Middle English verb lukken (“to chance, to happen by good fortune”) in the 15th century.

来源：wiktionary