"Celtic monumental stone," 1768, from Welsh llech, cognate with Gaelic and Irish leac (see cromlech).
"yen, strong desire" (especially sexual and sometimes implying perversion), 1796, variant of letch, but according to OED "now regarded as a back-formation" from lecher. Meaning "a lecher" is by 1943. As a verb by 1911. Related: Leched; leching.
"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.
"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.
"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.
<a href="https://www.etymonline.com/word/lech">Etymology of lech by etymonline</a>
Harper, D. (n.d.). Etymology of lech. Online Etymology Dictionary. Retrieved $(datetime), from https://www.etymonline.com/word/lech