submoron
subintellectual
subnormal
nonintellectual
submoronic
fool
divvie
drool bucket
birdbrain
stun
monkey
lackbrain
four oh four
subexpert
hammerhead
shithead
dunderhead
knucklehead
blockhead
numskull
fuckhead
lunkhead
dunce
muttonhead
idiot
loggerhead
bonehead
dumbass
lackluster
amateur
honyock
dipstick
dimwit
simple
doltish
gobe-mouche
gobemouche
simpleton
wally
dropkick
airhead
ignoranus
ungenius
nonvisionary
dull
not the sharpest tool in the shed
concrete-head
rube
muff
not the sharpest tool in the box
dipshidiot
nonphilosopher
not the sharpest knife in the drawer
dumb genius
yahoo
hayseed
yokel
jasper
stupid
chawbacon
brainlet
half-wit
bumpkin
hick
dumbling
halfwit
unteachable
nondescript
innumerate
jabroni
intellectually challenged
half-witted
dink
meathead
fledgling
coxcomb
cerebrally challenged
jack of all trades, master of none
fuzznut
simp
muggle
addlehead
cockbag
glaik
addle-brain
philosophe
harebrain
mooncalf
doilem
fuzznuts
dirtbrain
mouth breather
crackhead
blinkard
cacophrenic
short-witted
git
doofbag