What is the X in X-mas?
c.1600, "mixed with a foreign substance, impure; no longer simple or natural," past participle adjective from sophisticate (v.). Of persons, with a positive sense, "worldly-wise, discriminating, cultured," from 1895.
c.1400, "make impure by admixture," from Medieval Latin sophisticatus, past participle of sophisticare (see sophistication). From c.1600 as "corrupt, delude by sophistry;" from 1796 as "deprive of simplicity." Related: Sophisticated; sophisticating. As a noun meaning "sophisticated person" from 1921.