Merriam-Webster Collegiate Dictionary - stupid

 I. adjective  Etymology: Middle French ~e, from Latin ~us, from stupere to be numb, be astonished — more at type  Date: 1541  1.  a. slow of mind ; obtuse  b. given to unintelligent decisions or acts ; acting in an unintelligent or careless manner  c. lacking intelligence or reason ; brutish  2. dulled in feeling or sensation ; torpid still ~ from the sedative  3. marked by or resulting from unreasoned thinking or acting ; senseless a ~ decision  4.  a. lacking interest or point a ~ event  b. vexatious, exasperating the ~ car won't start  • ~ly adverb  • ~ness noun Synonyms:  ~, dull, dense, crass, dumb mean lacking in power to absorb ideas or impressions. ~ implies a slow-witted or dazed state of mind that may be either congenital or temporary ~ students just keeping the seats warm ~ with drink. dull suggests a slow or sluggish mind such as results from disease, depression, or shock monotonous work that leaves the mind dull. dense implies a thickheaded imperviousness to ideas too dense to take a hint. crass suggests a grossness of mind precluding discrimination or delicacy a crass, materialistic people. dumb applies to an exasperating obtuseness or lack of comprehension too dumb to figure out what's going on.  II. noun  Date: 1712 a ~ person