attention-deficit hyperactivity disorderatˌtention-ˌdeficit hyperacˈtivity disˌorder (also attention-deficit syndrome) noun [uncountable] medical (abbreviation ADHD) 
a medical condition that especially affects children. It causes them to be too active and to be unable to pay attention or be quiet for very long.
a medical condition that especially affects children. It causes them to be too active and to be unable to pay attention or be quiet for very long.