The Collaborative International Dictionary of English v.0.48:

Spleen \Spleen\, v. t.
   To dislke. [Obs.] --Bp. Hacket.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Spleen \Spleen\, n. [L. splen, Gr. ???? the milt or spleen,
   affection of the spleen; cf. L. lien, plihan, pl[imac]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.
      [1913 Webster]

   2. Anger; latent spite; ill humor; malice; as, to vent one's
      spleen.
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            In noble minds some dregs remain,
            Not yet purged off, of spleen and sour disdain.
                                                  --Pope.
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   3. A fit of anger; choler. --Shak.
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   4. A sudden motion or action; a fit; a freak; a whim. [Obs.
      or R.]
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            A thousand spleens bear her a thousand ways. --Shak.
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   5. Melancholy; hypochondriacal affections.
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            Bodies changed to various forms by spleen. --Pope.
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            There is a luxury in self-dispraise:
            And inward self-disparagement affords
            To meditative spleen a grateful feast. --Wordsworth.
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   6. A fit of immoderate laughter or merriment. [Obs.]
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            Thy silly thought enforces my spleen. --Shak.
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WordNet (r) 3.0 (2006):

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: spleen, lien]
    2: a feeling of resentful anger [syn: irascibility, short
       temper, spleen, quick temper]