The Collaborative International Dictionary of English v.0.48:

Neutral \Neu"tral\, a. [L. neutralis, fr. neuter. See Neuter.]
   1. Not engaged on either side; not taking part with or
      assisting either of two or more contending parties;
      neuter; indifferent.
      [1913 Webster]

            The heart can not possibly remain neutral, but
            constantly takes part one way or the other.
                                                  --Shaftesbury.
      [1913 Webster]

   2. Neither good nor bad; of medium quality; middling; not
      decided or pronounced.
      [1913 Webster]

            Some things good, and some things ill, do seem,
            And neutral some, in her fantastic eye. --Sir J.
                                                  Davies.
      [1913 Webster]

   3. (Biol.) Neuter. See Neuter, a., 3.
      [1913 Webster]

   4. (Chem.) Having neither acid nor basic properties; unable
      to turn red litmus blue or blue litmus red; -- said of
      certain salts or other compounds. Contrasted with acid,
      and alkaline.
      [1913 Webster]

   Neutral axis, Neutral surface (Mech.), that line or
      plane, in a beam under transverse pressure, at which the
      fibers are neither stretched nor compressed, or where the
      longitudinal stress is zero. See Axis.

   Neutral equilibrium (Mech.), the kind of equilibrium of a
      body so placed that when moved slighty it neither tends to
      return to its former position not depart more widely from
      it, as a perfect sphere or cylinder on a horizontal plane.


   Neutral salt (Chem.), a salt formed by the complete
      replacement of the hydrogen in an acid or base; in the
      former case by a positive or basic, in the latter by a
      negative or acid, element or radical.

   Neutral tint, a bluish gray pigment, used in water colors,
      made by mixing indigo or other blue some warm color. the
      shades vary greatly.

   Neutral vowel, the vowel element having an obscure and
      indefinite quality, such as is commonly taken by the vowel
      in many unaccented syllables. It is regarded by some as
      identical with the [u^] in up, and is called also the
      natural vowel, as unformed by art and effort; it is also
      called the indefinite vowel. It is symbolized in some
      phonetic alphabets by the schwa ([schwa]). See Guide to
      Pronunciation, [sect] 17.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Neutral \Neu"tral\, n.
   A person or a nation that takes no part in a contest between
   others; one who is neutral.
   [1913 Webster]

         The neutral, as far as commerce extends, becomes a
         party in the war.                        --R. G.
                                                  Harper.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Colorless \Col"or*less\, a.
   1. Without color; not distinguished by any hue; transparent;
      as, colorless water; a colorless gas.

   Note: [Narrower terms: ashen, bloodless, livid, lurid, pale,
         pallid, pasty, wan, waxen; neutral; white] [Also
         See: achromatic, colorless.]
         [1913 Webster + WordNet 1.5]

   2. Free from any manifestation of partial or peculiar
      sentiment or feeling; not disclosing likes, dislikes,
      prejudice, etc.; as, colorless music; a colorless style;
      definitions should be colorless.
      [1913 Webster]

   3. having lost its normal color.

   Note: [Narrower terms: blanched, etiolate, etiolated,
         whitened; bleached, faded, washed-out, washy;
         dimmed, dulled, grayed; dirty; dull, sober,
         somber, subfusc] colored

   Syn: colorless, uncolored, uncoloured.
        [WordNet 1.5 +PJC]

WordNet (r) 3.0 (2006):

neutral
    adj 1: having no personal preference; "impersonal criticism"; "a
           neutral observer" [syn: impersonal, neutral]
    2: having only a limited ability to react chemically; chemically
       inactive; "inert matter"; "an indifferent chemical in a
       reaction" [syn: inert, indifferent, neutral]
    3: not supporting or favoring either side in a war, dispute, or
       contest
    4: possessing no distinctive quality or characteristics [ant:
       negative, positive]
    5: having no hue; "neutral colors like black or white" [syn:
       achromatic, neutral] [ant: chromatic]
    6: lacking distinguishing quality or characteristics; "a neutral
       personality that made no impression whatever"
    7: having no net electric charge [syn: neutral,
       electroneutral]
    n 1: one who does not side with any party in a war or dispute

Moby Thesaurus II by Grady Ward, 1.0:

248 Moby Thesaurus words for "neutral":
   Hydromatic, Laodicean, Olympian, abstract, achromatic, achromic,
   aloof, anemic, anythingarian, apathetic, asexual, ashen, ashy,
   autarchic, autarkic, automatic transmission, autonomous, beige,
   bland, bled white, bloodless, broad, cadaverous, candid, castrated,
   centrist, changeable, chloranemic, cogwheel, cold, collective,
   colorless, compromiser, conservative, contemplative, cool, dead,
   deadly pale, deathly pale, detached, differential,
   differential gear, dim, dimmed, dingy, discolored, disinterested,
   dispassionate, do-nothing, dormant, drab, dull, ecru, emasculated,
   equitable, etiolated, eunuchized, even, evenhanded, exsanguinated,
   exsanguine, exsanguineous, faded, faint, fair, fallow, featureless,
   fence-sitter, fervorless, fifty-fifty, flat, free lance,
   free spirit, free trader, free-spirited, freethinker, freewheel,
   freewheeling, frigid, frustrated, gear, gear train, gearbox,
   gearing, gearshift, gearwheel, general, generalized, generic,
   ghastly, gray, haggard, half-and-half, halfhearted, high, hueless,
   hypochromic, idle, immobile, impartial, impersonal, impotent,
   inactive, indecisive, indefinite, independent, indeterminate,
   indifferent, indistinct, indistinguishable, individualist,
   individualistic, inert, infirm of purpose, infirm of will,
   inner-directed, insipid, intermediate, irresolute, isolationist,
   just, lackluster, laissez-aller, laissez-faire, latitudinarian,
   leaden, liberal, libertarian, libertine, livid, lofty, low,
   lukewarm, lurid, lusterless, mat, mealy, meditative,
   middle-of-the-roader, midway, milk-and-water, milky, moderate,
   moderationist, moderatist, motionless, muddy, mugwump, mugwumpian,
   mugwumpish, mushy, nebulous, neuter, nonaligned, noncommittal,
   noncommitted, nonpartisan, nonspecific, nothingarian, objective,
   on the fence, overdrive, pale, pale as death, pale-faced, pallid,
   paralytic, paralyzed, passive, pasty, perfunctory, procrastinating,
   quiescent, quietist, quietistic, rack, remote, removed, reverse,
   rugged individualist, sallow, self-contained, self-dependent,
   self-determined, self-directing, self-governed, self-governing,
   self-reliant, self-subsistent, self-sufficient, self-supporting,
   selfless, sexless, sickly, sovereign, stagnant, stagnating,
   standard transmission, standpat, static, stationary, stick shift,
   swing vote, synchromesh, tallow-faced, tasteless, tepid,
   third force, third world, third-force, third-world, toneless,
   transmission, unaffiliated, unallied, unbiased, uncharacterized,
   uncolored, uncommitted, uncommitted voter, undazzled,
   undifferentiated, uninfluenced, uninvolved, unjaundiced,
   unprejudiced, unprepossessed, unselfish, unsexed, unsexual,
   unspecified, unswayed, vague, vapid, vegetable, vegetative, wan,
   washed out, washed-out, watery, waxen, weak, whey-faced, white,
   wide, wishy-washy, withdrawn, zealless