lascivious adj.

1590s, from lascivious + -ness. An earlier noun form was lascivity (c. 1500); a later one was lascivency (1660s).

Old English lust "desire, appetite; inclination, pleasure; sensuous appetite," from Proto-Germanic *lustuz (source also of Old Saxon, Old Frisian, Dutch lust, German Lust, Old Norse lyst, Gothic lustus "pleasure, desire, lust"), abstract noun from PIE *las- "to be eager, wanton, or unruly" (source also of Latin lascivus "wanton, playful, lustful;" see lascivious).

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.