c. 1300, "sexual intercourse;" mid-14c., "lasciviousness, sinful self-indulgence;" late 14c., "sensual pleasure," from Old French luxurie "debauchery, dissoluteness, lust" (12c., Modern French luxure), from Latin luxuria "excess, extravagant living, profusion; delicacy" (source also of Spanish lujuria, Italian lussuria), from luxus "excess, extravagance; magnificence," probably a figurative use of luxus (adj.) "dislocated," which is related to luctari "wrestle, strain" (see reluctance).
The English word lost its pejorative taint 17c. Meaning "habit of indulgence in what is choice or costly" is from 1630s; that of "sumptuous surroundings" is from 1704; that of "something choice or comfortable beyond life's necessities" is from 1780. Used as an adjective from 1916.
In Lat. and in the Rom. langs. the word connotes vicious indulgence, the neutral sense of the Eng. 'luxury' being expressed by L. luxus, F. luxe, Sp. lujo, It. lusso. [OED]