Terminology used to define clinical cough is based on features such as duration, underlying causes, and associated characteristics such as whether the cough is "dry" or "productive." Terms such as "refractory chronic cough," "unexplained chronic cough," and "idiopathic cough" are commonly used to describe a cough that persists despite extensive investigation and therapeutic trials. The use of these terms, sometimes interchangeably, has led to a degree of confusion and with the emergence of the new clinical and mechanisitic concept associated with cough, "cough hypersensitivity syndrome," there is a need for some clarity in the nomenclature used to describe this condition.