A severe speech disorder shown by an inability to speak or a severe struggle to say something clearly: "Apraxia of speech is noticed when the oral-motor muscles of a patient don't or can't normally respond to commands from the brain or when the brain can't normally send such commands."

"Even when a person can understand what another person says, if he has apraxia of speech, he can't physically position his own speech muscles and the sequence of muscle movements that are necessary to produce understandable words or to say anything so others can recognize what he is trying to communicate."