The Collaborative International Dictionary of English v.0.48:

Nobleman \No"ble*man\, n.; pl. Noblemen.
   One of the nobility; a noble; a peer; one who enjoys rank
   above a commoner, either by virtue of birth, by office, or by
   patent.
   [1913 Webster]

WordNet (r) 3.0 (2006):

nobleman
    n 1: a titled peer of the realm [syn: Lord, noble,
         nobleman] [ant: Lady, noblewoman, peeress]

Moby Thesaurus II by Grady Ward, 1.0:

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



Easton's 1897 Bible Dictionary:

Nobleman
   (Gr. basilikos, i.e., "king's man"), an officer of state (John
   4:49) in the service of Herod Antipas. He is supposed to have
   been the Chuza, Herod's steward, whose wife was one of those
   women who "ministered unto the Lord of their substance" (Luke
   8:3). This officer came to Jesus at Cana and besought him to go
   down to Capernaum and heal his son, who lay there at the point
   of death. Our Lord sent him away with the joyful assurance that
   his son was alive.


The Devil's Dictionary (1881-1906):

NOBLEMAN, n.  Nature's provision for wealthy American minds ambitious
to incur social distinction and suffer high life.