From Middle English
lait,
layt,
leit,
leyt, from Old English
līġet,
līġetu,
līeġet (“lightning, flash of lightning”), from
Proto-Germanic *laugiþō (“lightning”), from
Proto-Indo-European *leuk- (“to shine”). Related to Old English
līeġ (“fire, flame, lightning”). Compare also Old High German
laugazan,
lōhazan (“to be red, shine, sparkle”),
Gothic [script?] (lauhatjan, “to lighten”). More at
lowe,
light.