Aspects of the Theory of Definition -- I / Preliminary Considerations -- Real and Nominal Definitions -- Primitive Concepts: Habits, Conventions, and Laws -- II / Definitional Desiderata -- Vagueness and the Desiderata for Definition -- Definition in a Quinean World -- III / Formal Developments -- Definitions and Definability -- Towards a General Theory of Identifiability -- IV / Epistemic Dimensions -- Epistemic Terms and the Aims of Epistemology -- Rational Definitions and Defining Rationality -- V / Specialized Conceptions -- Idealized Definitions in Physics and Idealized Dispositions -- Inverted Definitions and Their Uses -- VI / Disciplinary Conceptions -- Definitions in Law -- Defining the Divine -- Philosophical Analyses: An Explanation and Defense -- Index of Names -- Index of Subjects