The Collaborative International Dictionary of English v.0.48:

Fretful \Fret"ful\, a. [See 2d Fret.]
   Disposed to fret; ill-humored; peevish; angry; in a state of
   vexation; as, a fretful temper. -- Fret"ful*ly, adv. --
   Fret"ful*ness, n.

   Syn: Peevish; ill-humored; ill-natured; irritable; waspish;
        captious; petulant; splenetic; spleeny; passionate;
        angry.

   Usage: Fretful, Peevish, Cross. These words all
          indicate an unamiable working and expression of
          temper. Peevish marks more especially the inward
          spirit: a peevish man is always ready to find fault.
          Fretful points rather to the outward act, and marks a
          complaining impatience: sickly children are apt to be
          fretful. Crossness is peevishness mingled with
          vexation or anger.
          [1913 Webster]

WordNet (r) 3.0 (2006):

fretfulness
    n 1: an irritable petulant feeling [syn: irritability,
         crossness, fretfulness, fussiness, peevishness,
         petulance, choler]

Moby Thesaurus II by Grady Ward, 1.0:

28 Moby Thesaurus words for "fretfulness":
   anxiety, breathless impatience, chafing, disquietude, eagerness,
   excitement, fretting, haste, impatience, impatientness,
   impetuousness, lather, peevishness, pettishness, petulance,
   petulancy, querulousness, resentfulness, restiveness, restlessness,
   shrewishness, stew, sweat, tense readiness, uneasiness,
   unpatientness, unquietness, vixenishness