 The regionhood predicate is potentially useful in stating restricted versions of familiar mereological principles. One might want a principle to the effect that any plurality of regions has a fusion, while remaining neutral on the more general claim that any plurality of entities whatever has a fusion. Likewise one might want a principle to the effect that non-identical regions never mereologically coincide, while rejecting the stronger claim that non-identical entities in general never mereologically coincide. (Perhaps a certain clay statue mereologically coincides with, but is not identical to, a certain lump of clay.) The most natural formulations of these restricted principles employ a regionhood predicate. Though one might take this predicate as primitive, considerations of ideological parsimony provide some motivation for treating it as defined.