stupid
unintelligent
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
callous
deaf
eyeless
half-witted
heartless
illiterate
inconsequential
insensitive
insipid
irresponsible
mindless
nonsensical
pointless
senseless
soulless
thoughtless
unmeaning
vapid
witless
worthless