The term "neurosis" was coined by Scottish doctor William Cullen in 1769 to refer to "disorders of sense and motion" caused by a "general affection of the nervous system." Cullen used the term to describe various nervous disorders and symptoms that could not be explained physiologically. Physical features, however, were almost inevitably present, and physical diagnostic tests, such as exaggerated knee-jerks, loss of the gag reflex and dermatographia, were used into the 20th century. The meaning of the term was redefined by Carl Jung and Sigmund Freud over the early and middle 20th century, and has continued to be used in psychology and philosophy.