Diagnosis refers to: (1) the identification of a disorder from an examination of the symptoms; (2) investigation or analysis of the cause or nature of a condition, situation, or problem; (3) the art or act of identifying a disease from its signs and symptoms; and (4) critical perception or scrutiny; judgment based on such scrutiny; especially., perception of, or judgment concerning, motives and character.
Other /More definition:
diagnosis refers to the process of determining whether a presenting problem meets the established criteria for a specific psychological disorder.
Lexicon of Psychology - Terms, Treatments, Biographies,