The Collaborative International Dictionary of English v.0.48:

Shy \Shy\ (sh[imac]), a. [Compar. Shier (sh[imac]"[~e]r) or
   Shyer; superl. Shiest or Shyest.] [OE. schey, skey,
   sceouh, AS. sce['o]h; akin to Dan. sky, Sw. skygg, D. schuw,
   MHG. schiech, G. scheu, OHG. sciuhen to be or make timid. Cf.
   Eschew.]
   1. Easily frightened; timid; as, a shy bird.
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            The horses of the army . . . were no longer shy, but
            would come up to my very feet without starting.
                                                  --Swift.
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   2. Reserved; coy; disinclined to familiar approach.
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            What makes you so shy, my good friend? There's
            nobody loves you better than I.       --Arbuthnot.
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            The embarrassed look of shy distress
            And maidenly shamefacedness.          --Wordsworth.
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   3. Cautious; wary; suspicious.
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            I am very shy of using corrosive liquors in the
            preparation of medicines.             --Boyle.
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            Princes are, by wisdom of state, somewhat shy of
            thier successors.                     --Sir H.
                                                  Wotton.
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   4. Inadequately supplied; short; lacking; as, the team is shy
      two players.[Slang]
      [Webster 1913 Suppl.]

   5. (Poker), owing money to the pot; -- in cases where an
      opponent's bet has exceeded a player's available stake or
      chips, but the player chooses to continue playing the hand
      before adding the required bet to the pot. [Slang]
      [PJC]

   To fight shy. See under Fight, v. i.
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The Collaborative International Dictionary of English v.0.48:

Shy \Shy\, v. i. [imp. & p. p. Shied; p. pr. & vb. n.
   Shying.] [From Shy, a.]
   To start suddenly aside through fright or suspicion; -- said
   especially of horses.
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The Collaborative International Dictionary of English v.0.48:

Shy \Shy\, v. t.
   To throw sidewise with a jerk; to fling; as, to shy a stone;
   to shy a slipper. --T. Hughes.
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The Collaborative International Dictionary of English v.0.48:

Shy \Shy\, n.
   1. A sudden start aside, as by a horse.
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   2. A side throw; a throw; a fling. --Thackeray.
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            If Lord Brougham gets a stone in his hand, he must,
            it seems, have a shy at somebody.     --Punch.
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WordNet (r) 3.0 (2006):

shy
    adj 1: lacking self-confidence; "stood in the doorway diffident
           and abashed"; "problems that call for bold not timid
           responses"; "a very unsure young man" [syn: diffident,
           shy, timid, unsure] [ant: confident]
    2: short; "eleven is one shy of a dozen"
    3: wary and distrustful; disposed to avoid persons or things;
       "shy of strangers"
    n 1: a quick throw; "he gave the ball a shy to the first
         baseman"
    v 1: start suddenly, as from fright
    2: throw quickly