mid-15c., "lustful, inclined to lust," from Medieval Latin lasciviosus (used in a scolding sense by Isidore and other early Church writers), from Latin lascivia "lewdness, playfulness, fun, frolicsomeness, jolity," from lascivus "lewd, playful, undesigned, frolicsome, wanton."
This is from PIE *las-ko-, from the root *las- "to be eager, wanton, or unruly" (source also of Sanskrit -lasati "yearns," lasati "plays, frolics," Hittite ilaliya- "to desire, covet," Greek laste "harlot," Old Church Slavonic laska "flattery," Slovak laska "love," Russian lasyj "greedy, eager, affectionate," Old Irish lainn "greedy, eager," Gothic lustus, Old English lust "lust").
Meaning "tending to excite lust" is from 1580s. Related: Lasciviously. In 17c. also with a verbal form, lasciviate, now obsolete.
In Middle English, "any source of pleasure or delight," also "an appetite," also "a liking for a person," also "fertility" (of soil). Specific and pejorative sense of "sinful sexual desire, degrading animal passion" (now the main meaning) developed in late Old English from the word's use in Bible translations (such as lusts of the flesh to render Latin concupiscentia carnis in I John ii:16); the cognate words in other Germanic languages tend to mean simply "pleasure." Masculine in Old English, feminine in modern German.
late 15c., "smooth, slippery," also "lascivious, lewd," from French lubrique (15c.) or directly from Latin lubricus "slippery," figuratively "seductive," from PIE root *sleubh- "to slip, slide." Related: Lubrical.