The Collaborative International Dictionary of English v.0.48:

Cheer \Cheer\, v. t. [imp. & p. p. Cheered (ch[=e]rd); p. pr.
   & vb. n. cheering.]
   1. To cause to rejoice; to gladden; to make cheerful; --
      often with up. --Cowpe.
      [1913 Webster]

   2. To infuse life, courage, animation, or hope, into; to
      inspirit; to solace or comfort.
      [1913 Webster]

            The proud he tamed, the penitent he cheered.
                                                  --Dryden.
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   3. To salute or applaud with cheers; to urge on by cheers;
      as, to cheer hounds in a chase.
      [1913 Webster]

   To cheer ship, to salute a passing ship by cheers of
      sailors stationed in the rigging.

   Syn: To gladden; encourage; inspirit; comfort; console;
        enliven; refresh; exhilarate; animate; applaud.
        [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Cheer \Cheer\ (ch[=e]r), n. [OE. chere face, welcome, cheer, OF.
   chiere, F. ch[`e]re, fr. LL. cara face, Gr. ka`ra head; akin
   to Skr. [,c]iras, L. cerebrum brain, G. hirn, and E.
   cranium.]
   1. The face; the countenance or its expression. [Obs.] "Sweat
      of thy cheer." --Wyclif.
      [1913 Webster]

   2. Feeling; spirit; state of mind or heart.
      [1913 Webster]

            Be of good cheer.                     --Matt. ix. 2.
      [1913 Webster]

            The parents . . . fled away with heavy cheer.
                                                  --Holland.
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   3. Gayety; mirth; cheerfulness; animation.
      [1913 Webster]

            I have not that alacrity of spirit,
            Nor cheer of mind, that I was wont to have. --Shak.
      [1913 Webster]

   1. That which promotes good spirits or cheerfulness;
      provisions prepared for a feast; entertainment; as, a
      table loaded with good cheer.
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   5. A shout, hurrah, or acclamation, expressing joy
      enthusiasm, applause, favor, etc.
      [1913 Webster]

            Welcome her, thundering cheer of the street.
                                                  --Tennyson.
      [1913 Webster]

   What cheer? How do you fare? What is there that is
      cheering?
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Cheer \Cheer\, v. i.
   1. To grow cheerful; to become gladsome or joyous; -- usually
      with up.
      [1913 Webster]

            At sight of thee my gloomy soul cheers up. --A.
                                                  Philips.
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   2. To be in any state or temper of mind. [Obs.]
      [1913 Webster]

            How cheer'st thou, Jessica?           --Shak.
      [1913 Webster]

   3. To utter a shout or shouts of applause, triumph, etc.
      [1913 Webster]

            And even the ranks of Tusculum
            Could scare forbear to cheer.         --Macaulay.
      [1913 Webster]

WordNet (r) 3.0 (2006):

cheer
    n 1: a cry or shout of approval
    2: the quality of being cheerful and dispelling gloom; "flowers
       added a note of cheerfulness to the drab room" [syn:
       cheerfulness, cheer, sunniness, sunshine] [ant:
       uncheerfulness]
    v 1: give encouragement to [syn: cheer, hearten, recreate,
         embolden] [ant: dishearten, put off]
    2: show approval or good wishes by shouting; "everybody cheered
       the birthday boy"
    3: cause (somebody) to feel happier or more cheerful; "She tried
       to cheer up the disappointed child when he failed to win the
       spelling bee" [syn: cheer, cheer up, jolly along,
       jolly up]
    4: become cheerful [syn: cheer, cheer up, chirk up] [ant:
       complain, kick, kvetch, plain, quetch, sound off]
    5: spur on or encourage especially by cheers and shouts; "The
       crowd cheered the demonstrating strikers" [syn: cheer,
       root on, inspire, urge, barrack, urge on, exhort,
       pep up]

Moby Thesaurus II by Grady Ward, 1.0:

286 Moby Thesaurus words for "cheer":
   abide by, accede, accept, acclaim, acclamation, acquiesce,
   acquiesce in, afford hope, agree, agree to, agree with, alleluia,
   animate, applaud, applause, assent, assure, augur well, bark,
   battle cry, bawl, bear up, beatification, beatitude, bellow,
   bewitchment, bid fair, big hand, blessedness, bliss, blissfulness,
   blitheness, blithesomeness, board, bolster, boost, brace, brace up,
   bread, bread and butter, brighten, brightness, brisk, brisken,
   buck up, buoy up, buoyancy, burst of applause, buy, call,
   caterwaul, cheer on, cheer up, cheerfulness, cheeriness,
   cheery vein, chirk up, chorus of cheers, clap, clap the hands,
   clapping, clapping of hands, cloud nine, comestibles, comfort,
   comply, condole with, consent, consolation, console, conviviality,
   creature comfort, cry, cry for joy, cuisine, daily bread,
   delectation, delight, disposition, drive on, ease, eatables, eclat,
   ecstasy, ecstatics, edibles, egg on, elate, elation, embolden,
   enchantment, encore, encourage, encouragement, enliven,
   eupeptic mien, exaltation, exhilarate, exhilaration, exuberance,
   fare, fast food, feast, felicity, festivity, food, food and drink,
   foodstuff, fortify, frame of mind, fresh up, freshen, freshen up,
   gaiety, geniality, give a cheer, give a hand, give a lift,
   give comfort, give hope, give the nod, gladden, gladness,
   gladsomeness, glee, goad on, good cheer, hail, hallelujah, halloo,
   hand, handclap, handclapping, happiness, hasten on,
   have good prospects, health food, hear it for, hearten, heartiness,
   heaven, hie on, high spirits, hold out hope, hold out promise,
   hold with, holler, hollo, hooray, hoot, hopefulness, hosanna,
   hound on, howl, hurrah, hurray, hurry on, huzzah, in toto, ingesta,
   inspire, inspire hope, inspirit, intoxication, invigorate, jollity,
   joviality, joy, joyance, joyfulness, junk food, justify hope,
   kitchen stuff, lift up, liven, make fair promise, meat, merriment,
   merrymaking, mirth, nerve, nod, nod assent, optimism, ovation,
   overhappiness, overjoyfulness, paean, paradise, perk up, pick up,
   plaudit, pleasantness, popularity, promise, provender, provision,
   put at ease, quicken, radiance, rah, raise expectations,
   raise hope, rallying cry, rapture, ravishment, reanimate, reassure,
   receive, recreate, refresh, refreshen, regale, reinvigorate,
   rejoice, rejoice the heart, relieve, renew, revelry, revive,
   revivify, roar, root, root for, root on, rosy expectation,
   round of applause, sanguine humor, sanguineness, scream, screech,
   set at ease, set up, seventh heaven, shout, shout hosanna, shriek,
   solace, speed on, spirit, spread, spur on, squall, squawk, squeal,
   steel, stimulate, strengthen, subscribe to, sunniness, sunshine,
   support, sustenance, sympathize with, table, take kindly to,
   thunder of applause, transport, tucker, unalloyed happiness,
   uplift, urge on, viands, victuals, vitalize, vittles, vivify,
   vote for, war cry, war whoop, warm, welcome, whip on, whoop,
   winsomeness, yammer, yap, yawl, yawp, yell, yelp, yes,
   yield assent, yippee, yo-ho, yowl