On the definition of APD and the need for a conceptual model of terminology.

Objective: To consider the definition of auditory processing disorder (APD). Design: Narrative review and opinion piece. Study sample: Considerations of definition drawn primarily from the fields of philosophy, audition, learning and language.
Results: The problem of defining APD appears genuine. Current and previous definitions of APD are nominal in nature, being both stipulative (offering explicit and arbitrary adoptions of meaning relation between words) and operational (creating rules that stipulate how the terms might apply to particular cases). Such definitions survive by consensus and perceived heuristic value in a manner that fails to achieve closure as arguments about their validity remain relative.
Conclusion: A conceptual model of APD terminology is needed that considers nominal, conceptual and real definitions as well as different purposes for defining APD within professional and public domains. A framework for such a conceptual model of APD terminology is offered.