The Oxford Thesaurus An A-Z Dictionary of Synonyms - neutral adj.

1) non-belligerent, non-combatant, unaligned, non-aligned, unaffiliated, uninvolved, unallied, non-allied, non-partisan, impartial, disinterested, indifferent, dispassionate, unbiased, uncommitted, noncommittal, aloof, withdrawn, detached, remote, removed: Switzerland has remained neutral during both world wars. 2) dull, drab, colourless, achromatic, toneless, indeterminate, washed out, pale, indefinite, indistinct, indistinguishable, indeterminate, vague, drab, beige, ecru: A neutral wallpaper colour won't clash with the paintings.