The Collaborative International Dictionary of English v.0.48:

Excellent \Ex"cel*lent\, a. [F. excellent, L. excellens, -entis,
   p. pr. of excellere. See Excel.]
   1. Excelling; surpassing others in some good quality or the
      sum of qualities; of great worth; eminent, in a good
      sense; superior; as, an excellent man, artist, citizen,
      husband, discourse, book, song, etc.; excellent breeding,
      principles, aims, action.
      [1913 Webster]

            To love . . .
            What I see excellent in good or fair. --Milton.
      [1913 Webster]

   2. Superior in kind or degree, irrespective of moral quality;
      -- used with words of a bad significance. [Obs. or
      Ironical] "An excellent hypocrite." --Hume.
      [1913 Webster]

            Their sorrows are most excellent.     --Beau. & Fl.

   Syn: Worthy; choice; prime; valuable; select; exquisite;
        transcendent; admirable; worthy.
        [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Excellent \Ex"cel*lent\, adv.
   Excellently; eminently; exceedingly. [Obs.] "This comes off
   well and excellent." --Shak.
   [1913 Webster]

WordNet (r) 3.0 (2006):

excellent
    adj 1: very good;of the highest quality; "made an excellent
           speech"; "the school has excellent teachers"; "a first-
           class mind" [syn: excellent, first-class,
           fantabulous, splendid]

Moby Thesaurus II by Grady Ward, 1.0:

216 Moby Thesaurus words for "excellent":
   Al, Attic, Daedalian, Grade A, a cut above, above, adept,
   admirable, adroit, advantageous, aesthetic, aggrandized, ahead,
   apotheosized, apt, artistic, ascendant, auspicious, authoritative,
   awesome, bang-up, banner, beatified, beneficial, benevolent,
   better, big, blue-ribbon, bon, bonny, bonzer, boss, bravura, braw,
   brilliant, bueno, bully, bunkum, canonized, capital, capping,
   champion, chaste, choice, chosen, classic, classical, clean,
   clever, cogent, commendable, cool, coordinated, crack, crackerjack,
   cunning, cute, daedal, dandy, deft, deified, dexterous, dextrous,
   diplomatic, distinguished, eclipsing, elegant, elevated, eminent,
   ennobled, enshrined, enthroned, estimable, exalted, exceeding,
   excelling, exceptional, expedient, expert, extraordinary, fair,
   famous, fancy, fantastic, favorable, fine, finer, first-class,
   first-rate, first-string, glorified, good, goodish, goodly,
   graceful, grand, great, greater, handy, healthy, hear, held in awe,
   helpful, high, high and mighty, higher, immortal, immortalized,
   in ascendancy, in good taste, in the ascendant, ingenious, kind,
   laudable, lofty, magic, magisterial, magnified, major, marked,
   masterful, masterly, matchless, mighty, neat, nice, no mean, noble,
   nonpareil, notable, noteworthy, number one, of choice, of quality,
   one up on, ordinary, outstanding, over, par excellence, peerless,
   pleasant, pleasing, politic, prime, professional, proficient,
   profitable, pure, quality, quick, quiet, quite some, rare, ready,
   regal, remarkable, resourceful, restrained, ripping, rivaling,
   royal, sainted, sanctified, select, shrined, simple, skillful,
   slap-up, slick, smashing, some, sound, sovereign, splendid,
   statesmanlike, sterling, stunning, stylish, subdued, sublime,
   super, superb, supereminent, superior, superlative, supreme,
   surpassing, swingeing, tactful, tasteful, terrific, the best,
   the compleat, the complete, throned, top, top-hole, top-notch,
   topping, transcendent, transcendental, transcending, unaffected,
   understated, unobtrusive, upper, useful, valid, very good,
   virtuoso, virtuous, well-chosen, well-done, without equal,
   workmanlike, worthy