mid-13c., from Old French user "use, employ, practice," from Vulgar Latin *usare "use," frequentative form of past participle stem of Latin uti "to use," in Old Latin oeti "use, employ, exercise, perform," of unknown origin. Related: Used; using. Replaced Old English brucan (see brook (v.)).
early 13c., from Old French us, from Latin usus "use, custom, skill, habit," from past participle stem of uti (see use (v.)).
To use narcotics; take a dose or injection of a narcotic: I used this morning and I'm still nice (1950s+ Narcotics)