The Collaborative International Dictionary of English v.0.48:

Impatient \Im*pa"tient\ ([i^]m*p[=a]"shent), a. [OE. impacient,
   F. impatient, fr. L. impatiens; pref. im- not + patiens
   patient. See Patient.]
   1. Not patient; not bearing with composure; intolerant;
      uneasy; fretful; restless, because of pain, delay, or
      opposition; eager for change, or for something expected;
      hasty; passionate; -- often followed by at, for, of, and
      under.
      [1913 Webster]

            A violent, sudden, and impatient necessity. --Jer.
                                                  Taylor.
      [1913 Webster]

            Fame, impatient of extremes, decays
            Not more by envy than excess of praise. --Pope.
      [1913 Webster]

            The impatient man will not give himself time to be
            informed of the matter that lies before him.
                                                  --Addison.
      [1913 Webster]

            Dryden was poor and impatient of poverty.
                                                  --Macaulay.
      [1913 Webster]

   2. Not to be borne; unendurable. [Obs.] --Spenser.
      [1913 Webster]

   3. Prompted by, or exhibiting, impatience; as, impatient
      speeches or replies. --Shak.

   Syn: Restless; uneasy; changeable; hot; eager; fretful;
        intolerant; passionate.
        [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Impatient \Im*pa"tient\, n.
   One who is impatient. [R.]
   [1913 Webster]

WordNet (r) 3.0 (2006):

impatient
    adj 1: restless or short-tempered under delay or opposition;
           "impatient with the slower students"; "impatient of
           criticism" [ant: patient]
    2: (usually followed by `to') full of eagerness; "impatient to
       begin"; "raring to go" [syn: impatient(p), raring(p)]

Moby Thesaurus II by Grady Ward, 1.0:

73 Moby Thesaurus words for "impatient":
   abrupt, agitated, agog, alacritous, all agog, animated, antsy,
   antsy-pantsy, anxious, athirst, avid, breathless, brusque,
   bursting to, chafing, curt, demanding, desirous, eager, edgy,
   excited, fidgety, forward, fretful, fretting, full of life, hasty,
   headlong, hopped-up, hot-tempered, impetuous, impulsive,
   in a lather, in a stew, in a sweat, indignant, irascible,
   irritable, itchy, keen, lively, nervous, on edge, overhasty,
   panting, precipitate, prompt, querulous, quick, raring to, rash,
   ready, ready and willing, reckless, restive, restless, short,
   short-tempered, snappish, spirited, squirming, squirmy, sudden,
   testy, thirsty, uneasy, unpatient, unquiet, vital, vivacious,
   vivid, waspish, zestful