The Collaborative International Dictionary of English v.0.48:

affection \af*fec"tion\ ([a^]f*f[e^]k"sh[u^]n), n. [F.
   affection, L. affectio, fr. afficere. See Affect.]
   1. The act of affecting or acting upon; the state of being
      affected.
      [1913 Webster]

   2. (Philosophy) An attribute, especially a contingent or
      alterable quality or property; a condition; a bodily
      state; as, figure, weight, etc., are affections of bodies.
      "The affections of quantity." --Boyle.
      [1913 Webster]

            And, truly, waking dreams were, more or less,
            An old and strange affection of the house.
                                                  --Tennyson.
      [1913 Webster]

   3. Bent of mind; a feeling or natural impulse or natural
      impulse acting upon and swaying the mind; any emotion; as,
      the benevolent affections, esteem, gratitude, etc.; the
      malevolent affections, hatred, envy, etc.; inclination;
      disposition; propensity; tendency.
      [1913 Webster]

            Affection is applicable to an unpleasant as well as
            a pleasant state of the mind, when impressed by any
            object or quality.                    --Cogan.
      [1913 Webster]

   4. A settled good will; kind feeling; love; zealous or tender
      attachment; -- often in the pl. Formerly followed by to,
      but now more generally by for or towards; as, filial,
      social, or conjugal affections; to have an affection for
      or towards children.
      [1913 Webster]

            All his affections are set on his own country.
                                                  --Macaulay.
      [1913 Webster]

   5. Prejudice; bias. [Obs.] --Bp. Aylmer.
      [1913 Webster]

   6. (Med.) Disease; morbid symptom; malady; as, a pulmonary
      affection. --Dunglison. AS
      [1913 Webster]

   7. The lively representation of any emotion. --Wotton.
      [1913 Webster]

   8. Affectation. [Obs.] "Spruce affection." --Shak.
      [1913 Webster]

   9. Passion; violent emotion. [Obs.]
      [1913 Webster]

            Most wretched man,
            That to affections does the bridle lend. --Spenser.
      [1913 Webster]

   Syn: Attachment; passion; tenderness; fondness; kindness;
        love; liking; good will. See Attachment; Disease.
        [1913 Webster]

WordNet (r) 3.0 (2006):

affection
    n 1: a positive feeling of liking; "he had trouble expressing
         the affection he felt"; "the child won everyone's heart";
         "the warmness of his welcome made us feel right at home"
         [syn: affection, affectionateness, fondness,
         tenderness, heart, warmness, warmheartedness,
         philia]