The Only Use of

neutral
in
To Kill a Mockingbird

Mayella's hostility, which had subsided to grudging neutrality, flared again.
p. 208.8

neutrality = not favoring any side in a disagreement

Definitions:

(1) (neutral as in: played at a neutral site)
not favoring any side in a contest, war, disagreement, or other dispute
(2) (neutral as in: a carbon-neutral building)
not affected by; or does not affect
The expression [x] neutral means two things do not affect each other. More specifically, it means one of two things depending upon context:
- something is not affected by x -- for example "a revenue neutral tax plan" does not affect the amount of revenue collected. (It might raise taxes in one area and reduce them in another so that the total tax revenue is unchanged.)
- something does not affect x -- for example "a carbon neutral home" is a home that does not affect carbon. Part of its design might include using solar energy to control climate rather than burning fossil fuels.
(3) (neutral as in: decorated in neutral colors)
bland (not striking in appearance or impression)
(4) (neutral as in: Put the car in neutral.)
gears are not engaged; or (metaphorically) nothing is happening
(5) (meaning too rare to warrant focus)
meaning too rare to warrant focus:

Specialized senses typically mean that something does not belong to either of two other opposite alternatives; such as:
- chemistry: not acidic or alkaline
- physics: not with a positive charge or with a negative charge
- electric circuitry: with no voltage or electrical charge (though that is an informal simplification that would be dangerous if assumed in fact)