(a.) Having but little sense or shrewdness.

apish asinine batty befooled beguiled besotted buffoonish cockeyed crazy credulous daffy daft dazed dizzy doting dumb empty-headed fatuitous fatuous featherbrained featherheaded flaky fluttery fond fool foolheaded foolish frivolous fuddled futile gaga giddy giddy-brained giddy-headed giddy-pated giddy-witted goofy gulled harebrain harebrained headless idiotic ignorant imbecile inane inept infatuated insane insensate irrational kooky lackbrained lean-minded lean-witted loony mad maudlin mindless moronic nitwitted not bright nutty of little brain pea-brained pin-brained rattlebrained rattleheaded rattlepated reasonless sappy scatterbrained scramblebrained screwy senseless sentimental shatterbrained silly slackminded slackwitted stupid thoughtless ungifted unintellectual unintelligent unreasoning untalented unthinking unwise unwitty wacky weak-minded wet witless