The Collaborative International Dictionary of English v.0.48:

Sympathetic \Sym`pa*thet"ic\, a. [See Sympathy, and cf.
   Pathetic.]
   1. Inclined to sympathy; sympathizing.
      [1913 Webster]

            Far wiser he, whose sympathetic mind
            Exults in all the good of all mankind. --Goldsmith.
      [1913 Webster]

   2. Produced by, or expressive of, sympathy.
      [1913 Webster]

            Ope the sacred source of sympathetic tears. --Gray.
      [1913 Webster]

   3. (Physiol.)
      (a) Produced by sympathy; -- applied particularly to
          symptoms or affections. See Sympathy.
      (b) Of or relating to the sympathetic nervous system or
          some of its branches; produced by stimulation on the
          sympathetic nervious system or some part of it; as,
          the sympathetic saliva, a modified form of saliva,
          produced from some of the salivary glands by
          stimulation of a sympathetic nerve fiber.
          [1913 Webster]

   Sympathetic ink. (Chem.) See under Ink.

   Sympathetic nerve (Anat.), any nerve of the sympathetic
      system; especially, the axial chain of ganglions and
      nerves belonging to the sympathetic system.

   Sympathetic powder (Alchemy), a kind of powder long
      supposed to be able to cure a wound if applied to the
      weapon that inflicted it, or even to a portion of the
      bloody clothes. --Dunglison.

   Sympathetic sounds (Physics), sounds produced from solid
      bodies by means of vibrations which have been communicated
      to them from some other sounding body, by means of the air
      or an intervening solid.

   Sympathetic system (Anat.), a system of nerves and nerve
      ganglions connected with the alimentary canal, the
      vascular system, and the glandular organs of most
      vertebrates, and controlling more or less their actions.
      The axial part of the system and its principal ganglions
      and nerves are situated in the body cavity and form a
      chain of ganglions on each side of the vertebral column
      connected with numerous other ganglions and nerve
      plexuses.
      [1913 Webster]

WordNet (r) 3.0 (2006):

sympathetic
    adj 1: of or relating to the sympathetic nervous system;
           "sympathetic neurons"; "sympathetic stimulation"
    2: expressing or feeling or resulting from sympathy or
       compassion or friendly fellow feelings; disposed toward;
       "sympathetic to the students' cause"; "a sympathetic
       observer"; "a sympathetic gesture" [ant: unsympathetic]
    3: showing or motivated by sympathy and understanding and
       generosity; "was charitable in his opinions of others";
       "kindly criticism"; "a kindly act"; "sympathetic words"; "a
       large-hearted mentor" [syn: charitable, benevolent,
       kindly, sympathetic, good-hearted, openhearted,
       large-hearted]
    4: (of characters in literature or drama) evoking empathic or
       sympathetic feelings; "the sympathetic characters in the
       play" [syn: sympathetic, appealing, likeable,
       likable] [ant: unappealing, unlikable, unlikeable,
       unsympathetic]
    5: having similar disposition and tastes; "with their many
       similar tastes, he found her a most sympathetic companion"
    6: relating to vibrations that occur as a result of vibrations
       in a nearby body; "sympathetic vibration" [syn: harmonic,
       sympathetic]

Moby Thesaurus II by Grady Ward, 1.0:

155 Moby Thesaurus words for "sympathetic":
   Christian, Christlike, Christly, accordant, adductive,
   affectionate, affinitive, agreeable, agreeing, akin, allergic,
   alluring, amenable, amicable, anaphylactic, appertaining,
   associative, assuring, at one, attracting, attractive, attrahent,
   attuned, benign, benignant, bleeding, brotherly, charitable,
   cheering, clement, comforting, commiserative, comparable,
   comparative, compassionate, compatible, comprehending, concordant,
   condolatory, condolent, condoling, congenial, congruous,
   connective, consistent, consolatory, consoling, correlative,
   corresponding, decent, delicate, dragging, drawing, emotionable,
   empathetic, empathic, en rapport, encouraging, favorable,
   favorably disposed, forbearant, fraternal, frictionless, friendly,
   gentle, good, goosy, gracious, harmonious, heartening, hospitable,
   human, humane, hyperesthetic, hyperpathic, hypersensitive,
   impressionable, in accord, in concert, in rapport, in tune,
   inharmony, irritable, itchy, kind, kindhearted, kindly,
   kindly-disposed, lenient, like-minded, linking, loving, magnetic,
   magnetized, melting, merciful, nervous, nice, of good comfort,
   of one mind, open, open-minded, overrefined, oversensible,
   oversensitive, overtender, passible, peaceful, pertaining,
   pertinent, pitying, pleasant, prickly, proportionable,
   proportional, proportionate, pulling, reassuring, receptive,
   referable, referring, refined, relating, relational, relative,
   relieving, responsive, ruthful, sensible, sensitive, sib,
   simpatico, skittish, soft, softhearted, supersensitive, supportive,
   susceptible, sympathizing, tactful, tender, tenderhearted, tetchy,
   thin-skinned, ticklish, together, touchy, tugging, understanding,
   united, warm, warmhearted, well-disposed, well-intentioned,
   well-meaning