eminence (n.) Look up eminence at Dictionary.com
c. 1400, "projection, protuberance;" early 15c., "high or exalted position," from Old French eminence or directly from Latin eminentia "a distinctive feature, conspicuous part," from eminentem (nominative eminens) "standing out, projecting," figuratively, "prominent, distinctive" (see eminent).

As a title of honor (now only of cardinals) it is attested from 1650s. The original Éminence grise (French, literally "gray eminence") was François Leclerc du Trembley (1577-1638), confidential agent of Richelieu.