The Collaborative International Dictionary of English v.0.48:

Discard \Dis*card"\, v. i. (Card Playing)
   To make a discard.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Discard \Dis*card"\, n. (Card Playing)
   The act of discarding; also, the card or cards discarded.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Discard \Dis*card"\, v. t. [imp. & p. p. Discarded; p. pr. &
   vb. n. Discarding.]
   1. (Card Playing) To throw out of one's hand, as superfluous
      cards; to lay aside (a card or cards).
      [1913 Webster]

   2. To cast off as useless or as no longer of service; to
      dismiss from employment, confidence, or favor; to
      discharge; to turn away.
      [1913 Webster]

            They blame the favorites, and think it nothing
            extraordinary that the queen should . . . resolve to
            discard them.                         --Swift.
      [1913 Webster]

   3. To put or thrust away; to reject.
      [1913 Webster]

            A man discards the follies of boyhood. --I. Taylor.

   Syn: To dismiss; displace; discharge; cashier.
        [1913 Webster]

WordNet (r) 3.0 (2006):

discard
    n 1: anything that is cast aside or discarded
    2: (cards) the act of throwing out a useless card or of failing
       to follow suit
    3: getting rid something that is regarded as useless or
       undesirable [syn: discard, throwing away]
    v 1: throw or cast away; "Put away your worries" [syn:
         discard, fling, toss, toss out, toss away, chuck
         out, cast aside, dispose, throw out, cast out,
         throw away, cast away, put away]

Moby Thesaurus II by Grady Ward, 1.0:

191 Moby Thesaurus words for "discard":
   abandon, abdicate, abjuration, abjure, abjurement, back out,
   beg off, boot out, bounce, brush aside, cashier, cast, cast aside,
   cast away, cast off, cast out, cast-off, castaway, castoff, chuck,
   chuck out, chucking, chucking out, clearance, contemn, contempt,
   contradict, contradiction, cry off, declination, decline,
   declining, deep six, deep-six, defenestrate, denial, deny,
   depart from, deportation, derelict, despisal, despise, despising,
   detachment, detrude, dice, disapproval, disapprove, discarding,
   discharge, disclaim, disclamation, discount, discounting, disdain,
   disjunction, dismiss, dismissal, disown, disownment, dispense with,
   disposal, dispose of, disposition, disregard, ditch, dogie,
   drop out, dump, dumping, eighty-six, eject, ejection, eliminate,
   elimination, eradication, evacuate, except, exception, exclude,
   exclusion, exile, expatriation, expel, expulsion, extrude, flotsam,
   flotsam and jetsam, forsake, forswear, foundling, get quit of,
   get rid of, get shut of, give away, give the hook, go back on,
   heave out, ignore, ignoring, jetsam, jettison, jilt, junk, junking,
   kick downstairs, kick out, lagan, lay aside, leave, leave behind,
   leave flat, liquidation, maroon, nonacceptance, nonapproval,
   nonconsideration, obtrude, orphan, ostracism, oust, outlawing,
   outlawry, part with, pass by, pass up, passing by, pull out, purge,
   push aside, put out, putting away, putting out, quit, quit cold,
   rebuff, recant, recantation, refusal, refuse, refuse to consider,
   reject, rejectamenta, rejection, removal, remove, renege, renounce,
   renouncement, repel, repudiate, repudiation, repulse, riddance,
   rubbish, say goodbye to, scout, scouting, scrap, scrapping,
   severance, shed, shoot, shove away, slough, spurn, spurning,
   stand down, suspension, take leave of, throw, throw away,
   throw out, throw over, throw overboard, throwaway, throwing out,
   thrust out, toss out, toss overboard, trash, turn away, turn out,
   turning out, vacate, waif, waifs and strays, waive, wastrel,
   withdraw, withdrawal