A widely shared intuition says moral statements like “Aborting at 150 days is permissible” seem vague. But what is the nature of such vagueness? This article proposes a novel, shifty semantic account of moral vagueness which argues: Moral vagueness is essentially a semantic phenomenon existing in our imperfect (moral) language; the referents of vague moral terms may shift under the right circumstance; our usage of vague moral terms may contribute to such shifts, but so may some factors beyond our control. (...) After the account is fleshed out, some distinctions will be drawn to differentiate it from other accounts of moral vagueness, and more importantly, efforts will be made to reconcile this account and moral realism. In conclusion, my account is by far the first (minimal) moral realism-friendly shifty semantic account of moral vagueness that successfully explains our intuitions about vague moral statements. (shrink)