The Collaborative International Dictionary of English v.0.48:
Simple-minded \Sim"ple-mind`ed\, a. Artless; guileless; simple-hearted; undesigning; unsuspecting; devoid of duplicity. --Blackstone. -- Sim"ple-mind`ed*ness, n. [1913 Webster]WordNet (r) 3.0 (2006):
simple-minded adj 1: lacking subtlety and insight; "a simple-minded argument" 2: lacking mental capacity and subtlety [syn: dim-witted, simple, simple-minded]