The Collaborative International Dictionary of English v.0.48:

Choler \Chol"er\, n. [OE. coler, F. col[`e]re anger, L. cholera
   a bilious complaint, fr. Gr. ? cholera, fr. ?, cholh`, bile.
   See Gall, and cf. Cholera.]
   1. The bile; -- formerly supposed to be the seat and cause of
      irascibility. [Obs.]
      [1913 Webster]

            His [Richard Hooker's] complexion . . . was
            sanguine, with a mixture of choler; and yet his
            motion was slow.                      --I. Warton.
      [1913 Webster]

   2. Irritation of the passions; anger; wrath.
      [1913 Webster]

            He is rash and very sudden in choler. --Shak.
      [1913 Webster]

WordNet (r) 3.0 (2006):

choler
    n 1: an irritable petulant feeling [syn: irritability,
         crossness, fretfulness, fussiness, peevishness,
         petulance, choler]
    2: a strong emotion; a feeling that is oriented toward some real
       or supposed grievance [syn: anger, choler, ire]
    3: a humor that was once believed to be secreted by the liver
       and to cause irritability and anger [syn: yellow bile,
       choler]

Moby Thesaurus II by Grady Ward, 1.0:

32 Moby Thesaurus words for "choler":
   acerbity, acid, acidity, acidulousness, acrimony, anger, animosity,
   asperity, bad humor, bad temper, bile, biliousness,
   bitter resentment, bitterness, bitterness of spirit, causticity,
   corrosiveness, discontent, gall, gnashing of teeth, hard feelings,
   heartburning, ill humor, ill nature, ill temper, rancor, rankling,
   slow burn, soreness, sourness, spleen, virulence