 Before we address these questions, let us take note of a distinction that is not marked in logic books but which is useful in thinking about definitions. In one kind of definition—call it homogeneous definition—the defined term and the definiendum belong to the same logical category. So, a singular term is defined via a singular term; a general term via a general term; a sentence via a sentence; and so on. Let us say that a homogenous definition is regular iff its definiendum is identical to the defined term. Here are some examples of regular homogeneous definitions: