The Collaborative International Dictionary of English v.0.48:

Anxiety \Anx*i"e*ty\, n.; pl. Anxieties. [L. anxietas, fr.
   anxius: cf. F. anxi['e]t['e]. See Anxious.]
   1. Concern or solicitude respecting some thing or event,
      future or uncertain, which disturbs the mind, and keeps it
      in a state of painful uneasiness.
      [1913 Webster]

   2. Eager desire. --J. D. Forbes
      [1913 Webster]

   3. (Med.) A state of restlessness and agitation, often with
      general indisposition and a distressing sense of
      oppression at the epigastrium. --Dunglison.
      [1913 Webster]

   Syn: Care; solicitude; foreboding; uneasiness; perplexity;
        disquietude; disquiet; trouble; apprehension;
        restlessness. See Care.
        [1913 Webster]

WordNet (r) 3.0 (2006):

anxiety
    n 1: (psychiatry) a relatively permanent state of worry and
         nervousness occurring in a variety of mental disorders,
         usually accompanied by compulsive behavior or attacks of
         panic [syn: anxiety, anxiousness]
    2: a vague unpleasant emotion that is experienced in
       anticipation of some (usually ill-defined) misfortune