The Collaborative International Dictionary of English v.0.48:

Impatience \Im*pa"tience\n. [OE. impacience, F. impatience, fr.
   L. impatientia.]
   The quality of being impatient; lack of endurance of pain,
   suffering, opposition, or delay; eagerness for change, or for
   something expected; restlessness; chafing of spirit;
   fretfulness; passion; as, the impatience of a child or an
   invalid.
   [1913 Webster]

         I then, . . .
         Out of my grief and my impatience,
         Answered neglectingly.                   --Shak.
   [1913 Webster]

         With huge impatience he inly swelt
         More for great sorrow that he could not pass,
         Than for the burning torment which he felt. --Spenser.
   [1913 Webster]

WordNet (r) 3.0 (2006):

impatience
    n 1: a lack of patience; irritation with anything that causes
         delay [syn: restlessness, impatience]
    2: a restless desire for change and excitement
    3: a dislike of anything that causes delay [ant: forbearance,
       longanimity, patience]