1) Defect of speech 2) Speech defect 3) Speech disorder 
inability to express ideas due to mental incompetence
Impairment of speech and reasoning as the result of a mental disorder. ... Origin: dys-+ G. Logos, speaking, reason ... (05 Mar 2000) ... 
(dis-lo´jә) impairment of speech due to a mental disorder.
Type: Term Pronunciation: dis-lō′jē-ă Definitions: 1. Impairment of speech and reasoning as the result of a mental disorder.
[n] - impaired ability to express ideas verbally
dyslogia 1. Impairment of speech and reasoning as the result of a mental disorder. 2. Impairment of reasoning powers marked by an inability to express ideas in speech.
noun impaired ability to express ideas verbally; usually resulting from difficulties of reasoning (as in feeblemindedness or certain psychoses)
inability to express ideas because of faulty reasoning or speech, due to a mental disorder.