1754, "of the nature of a palace, magnificent," from French palatial "magnificent," from Latin palatium (see palace). Related: Palatially. Middle English had palasin in the literal sense of "belonging to a palace or court" (c. 1400, from Old French), which was revived in that sense in 19c. as palatian (1845). An earlier word for "magnificent, of the nature of a palace" was palacious (1620s), now obsolete.
