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