The Collaborative International Dictionary of English v.0.48:

Sycophant \Syc"o*phant\, n. [L. sycophanta a slanderer,
   deceiver, parasite, Gr. ? a false accuser, false adviser,
   literally, a fig shower; ? a fig + ? to show: cf. F.
   sycophante. The reason for the name is not certainly known.
   See Phenomenon.]
   1. An informer; a talebearer. [Obs.] "Accusing sycophants, of
      all men, did best sort to his nature." --Sir P. Sidney.
      [1913 Webster]

   2. A base parasite; a mean or servile flatterer; especially,
      a flatterer of princes and great men.
      [1913 Webster]

            A sycophant will everything admire:
            Each verse, each sentence, sets his soul on fire.
                                                  --Dryden.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Sycophant \Syc"o*phant\, v. t. [CF. L. sycophantari to deceive,
   to trick, Gr. ?.]
   1. To inform against; hence, to calumniate. [Obs.]
      [1913 Webster]

            Sycophanting and misnaming the work of his
            adversary.                            --Milton.
      [1913 Webster]

   2. To play the sycophant toward; to flatter obsequiously.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Sycophant \Syc"o*phant\, v. i.
   To play the sycophant.
   [1913 Webster]

WordNet (r) 3.0 (2006):

sycophant
    n 1: a person who tries to please someone in order to gain a
         personal advantage [syn: sycophant, toady, crawler,
         lackey, ass-kisser]

Moby Thesaurus II by Grady Ward, 1.0:

75 Moby Thesaurus words for "sycophant":
   adherent, adulator, apple-polisher, ass-licker, backscratcher,
   backslapper, blarneyer, bootlick, bootlicker, bootlicking,
   brown-nose, brownie, cajoler, clawback, courtier, cowering,
   creature, cringer, cringing, disciple, dummy, dupe, fawner,
   figurehead, flatterer, flunky, follower, footlicker, gillie, goon,
   gopher, groveler, groveling, handshaker, hanger-on, helot,
   henchman, instrument, jackal, kowtower, kowtowing, lackey,
   led captain, lickspit, lickspittle, man, mealymouth, minion,
   myrmidon, parasitic, peon, puppet, reptile, satellite, self-seeker,
   serf, slave, snob, spaniel, stooge, suck, thug, timeserver, toad,
   toadeater, toady, toadying, toadyish, tool, truckler, truckling,
   tufthunter, votary, wheedler, yes-man



The Devil's Dictionary (1881-1906):

SYCOPHANT, n.  One who approaches Greatness on his belly so that he
may not be commanded to turn and be kicked.  He is sometimes an
editor.

    As the lean leech, its victim found, is pleased
    To fix itself upon a part diseased
    Till, its black hide distended with bad blood,
    It drops to die of surfeit in the mud,
    So the base sycophant with joy descries
    His neighbor's weak spot and his mouth applies,
    Gorges and prospers like the leech, although,
    Unlike that reptile, he will not let go.
    Gelasma, if it paid you to devote
    Your talent to the service of a goat,
    Showing by forceful logic that its beard
    Is more than Aaron's fit to be revered;
    If to the task of honoring its smell
    Profit had prompted you, and love as well,
    The world would benefit at last by you
    And wealthy malefactors weep anew --
    Your favor for a moment's space denied
    And to the nobler object turned aside.
    Is't not enough that thrifty millionaires
    Who loot in freight and spoliate in fares,
    Or, cursed with consciences that bid them fly
    To safer villainies of darker dye,
    Forswearing robbery and fain, instead,
    To steal (they call it "cornering") our bread
    May see you groveling their boots to lick
    And begging for the favor of a kick?
    Still must you follow to the bitter end
    Your sycophantic disposition's trend,
    And in your eagerness to please the rich
    Hunt hungry sinners to their final ditch?
    In Morgan's praise you smite the sounding wire,
    And sing hosannas to great Havemeyher!
    What's Satan done that him you should eschew?
    He too is reeking rich -- deducting _you_.