neutral

from The American Heritage® Dictionary of the English Language, 5th Edition.

• adjective Not aligned with, supporting, or favoring either side in a war, dispute, or contest.
• adjective Belonging to neither side in a controversy.
• adjective Belonging to neither kind; not one thing or the other.
• adjective Sexless; neuter.
• adjective Of or relating to a solution or compound that is neither acidic nor alkaline.
• adjective Of or relating to a compound that does not ionize in solution.
• adjective Of or relating to a particle, an object, or a system that has neither positive nor negative electric charge.
• adjective Of or relating to a particle, object, or system that has a net electric charge of zero.
• adjective Of or indicating a color, such as gray, black, or white, that lacks hue; achromatic.
• adjective Linguistics Pronounced with the tongue in a middle position, neither high nor low, as the a in around.
• noun A nation nonaligned with either side in a war.
• noun A citizen of such a nation.
• noun One who takes no side in a controversy.
• noun A neutral hue.
• noun A position in which a set of gears is disengaged so that power cannot be transmitted.

from The Century Dictionary.

• In metallurgy:
• Neither acid nor basic: said of slag and linings.
• Neither red-short nor cold-short: said of wrought-iron.
• Suitable for production of neutral iron: said of iron-ore.
• See zone.
• noun Specifically, in some United States colleges and universities, one who belongs to none of the Greek-letter or other secret societies.
• noun In electricity, the neutral conductor of a three-wire circuit.
• In the condition of one who refrains from taking sides in a contest or dispute; taking no active part with either of two contestants or belligerents; not engaged on or interfering with either side.
• Belonging to a neutral state: as, neutral ships; a neutral flag.
• Neither one thing nor the other; intermediate; indifferent; mediocre.
• In chem., exhibiting neither acid nor alkaline qualities: as, neutral salts.
• In botany, sexless; having neither stamens nor pistils, as the ray-flowers of many Composite, the marginal flowers of Hydrangea, and the upper florets of many grasses. See cut under Hydrangea.
• In electricity and magnetism, not electrified; not magnetized.
• In color, of low chroma; without positive quality of color; grayish.
• noun A person, party, or nation that takes no part in a contest between others; one who or that which occupies a neutral or indifferent position.

from the GNU version of the Collaborative International Dictionary of English.

• adjective Not engaged on either side; not taking part with or assisting either of two or more contending parties; neuter; indifferent.
• adjective Neither good nor bad; of medium quality; middling; not decided or pronounced.
• adjective (Biol.) Neuter. See Neuter, a., 3.
• adjective (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.
• adjective (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.
• adjective (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.
• adjective (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.
• adjective a bluish gray pigment, used in water colors, made by mixing indigo or other blue some warm color. the shades vary greatly.
• adjective 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 ŭ 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 (ə). See Guide to Pronunciation, § 17.
• noun A person or a nation that takes no part in a contest between others; one who is neutral.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• adjective Not taking sides in a conflict such as war; nonaligned.
• adjective Favouring neither the supporting nor opposing viewpoint of a topic of debate; unbiased.
• adjective grammar Neither positive nor negative.
• adjective Neither beneficial nor harmful.
• adjective Having no sex; neuter.
• adjective Having no obvious colour; gray