unintelligent
nonintelligent
dim
unintellectual
dull
underbrained
unintelligence
stupidass
lackluster
stupid
gormless
vacancy
nonintellectual
halfwit
unintellectualized
not the sharpest tool in the shed
not the sharpest knife in the drawer
not the sharpest tool in the box
vacuous
unbright
ungenius
mindless
vacant
simple-mindedly
nonsmart
mentally challenged
ungeeky
intellectually challenged
inadept
cerebrally challenged
slow-witted
brainless
unsmartness
half-witted
unsmart
unskillful
ineducable
nonintelligence
inarticulable
short-witted
nonskilled
unignitible
subintellectual
nonsavvy
earthbound
prosaic
prosy
doltish
unclever
pedestrian