attention deficit disorder (n.) Look up attention deficit disorder at
(abbreviated ADD), introduced as a diagnosis in the third edition of the "Diagnostic and Statistical Manual of Mental Disorders" (1980), from attention in the "power of mental concentration" sense. Expanded to attention deficit hyperactivity disorder ("the co-existence of attentional problems and hyperactivity, with each behavior occurring infrequently alone;" ADHD) in DSM-III (1987).