Origin and history of lech

"structure consisting of a large, flat, unhewn stone resting horizontally atop three or more upright ones," c. 1600, from Welsh, from crom, fem. of crwm "crooked, bent, concave" + llech "(flat) stone." Applied in Wales and Cornwall to what in Brittany is a dolmen; a cromlech there is part of a circle of standing stones.

"lustful man, man given to excessive sexual indulgence," late 12c., from Old French lecheor (Modern French lécheur) "one living a life of debauchery," especially "one given to sexual indulgence," literally "licker," agent noun from lechier "to lick;" also "to live in debauchery or gluttony," from Frankish *likkon or some other Germanic source, from Proto-Germanic *likkojan "to lick" (from PIE root *leigh- "to lick"). The Old French feminine form was lechiere. Middle English, meanwhile, had lickestre "female who licks;" figuratively "a pleasure seeker," literally "lickster," with -ster. In 18c. sometimes leacher (Bailey), along with leacherous, leachery.

"craving, longing, strong desire," 1796 [Grose], perhaps a back-formation from lecher, or deformed from a figurative use of latch (v.) in a secondary sense of "grasp, grasp on to." Or perhaps from letch (v.), a variant of leach.