From ACT Wiki
An action or policy having no effect on a measure under review, having no net effect on it, or intended to have no net effect on it.
For example, carbon-neutral or neutral interest rate.
2. Risk management - hedging.
A position that is considered to be hedged against changes in a market rate or price, or other market-related variable.
For example, delta neutral or vega neutral.
3. Financial reporting.
Financial amounts reported on an adjusted basis to remove distortions and aid comparability.
For example, FX-neutral financial amounts.
4. Valuation or policy basis.
A basis of valuation or decision making that is independent of the variable mentioned.
For example, risk neutral valuation methods.