The Collaborative International Dictionary of English v.0.48:

Grandee \Gran*dee"\, n. [Sp. grande. See Grand.]
   A man of elevated rank or station; a nobleman. In Spain, a
   nobleman of the first rank, who may be covered in the king's
   presence.
   [1913 Webster]

WordNet (r) 3.0 (2006):

grandee
    n 1: a nobleman of highest rank in Spain or Portugal

Moby Thesaurus II by Grady Ward, 1.0:

39 Moby Thesaurus words for "grandee":
   Brahman, archduke, aristocrat, armiger, baron, baronet, blue blood,
   count, daimio, duke, earl, esquire, gentleman, grand duke, hidalgo,
   lace-curtain, laird, landgrave, lord, lordling, magnate, magnifico,
   margrave, marquis, noble, nobleman, optimate, palsgrave, patrician,
   peer, seigneur, seignior, silk-stocking, squire, swell,
   thoroughbred, upper-cruster, viscount, waldgrave