Merriam-Webster's Collegiate® Dictionary, 11th Edition
STUPID
I. adjective see: type
Date: 1541
1. slow of mind ; obtuse , given to unintelligent decisions or acts ; acting in an unintelligent or careless manner, lacking intelligence or reason ; brutish , dulled in feeling or sensation ; torpid , marked by or resulting from unreasoned thinking or acting ; senseless ,
4. lacking interest or point , vexatious , exasperating , stupidly adverb stupidness noun Synonyms: see: stupid
II. noun
Date: 1712
a stupid person