Source : Webster's Revised Unabridged Dictionary (1913)

Spleen \Spleen\, v. t.
   To dislke. [Obs.] --Bp. Hacket.

Spleen \Spleen\, n. [L. splen, Gr. ???? the milt or spleen,
   affection of the spleen; cf. L. lien, plihan, pl[=i]han.]
   1. (Anat.) A peculiar glandlike but ductless organ found near
      the stomach or intestine of most vertebrates and connected
      with the vascular system; the milt. Its exact function in
      not known.

   2. Anger; latent spite; ill humor; malice; as, to vent one's
      spleen.

            In noble minds some dregs remain, Not yet purged
            off, of spleen and sour disdain.      --Pope.

   3. A fit of anger; choler. --Shak.

   4. A sudden motion or action; a fit; a freak; a whim. [Obs.
      or R.]

            A thousand spleens bear her a thousand ways. --Shak.

   5. Melancholy; hypochondriacal affections.

            Bodies changed to various forms by spleen. --Pope.

            There is a luxury in self-dispraise: And inward
            self-disparagement affords To meditative spleen a
            grateful feast.                       --Wordsworth.

   6. A fit of immoderate laughter or merriment. [Obs.]

            Thy silly thought enforces my spleen. --Shak.

Source : WordNet®

spleen
     n 1: a large dark-red oval organ on the left side of the body
          between the stomach and the diaphragm; produces cells
          involved in immune responses [syn: {lien}]
     2: a feeling of resentful anger [syn: {irascibility}, {short
        temper}, {quick temper}]