dim
unintelligent
nonintelligent
dull
nonsmart
unsmart
lackluster
unsmartness
stupidass
unbright
unintellectual
vacancy
unclever
underbrained
gormless
half-witted
ungroomed
unintelligence
short-witted
ungeeky
nonsavvy
stupid
not the sharpest knife in the drawer
halfwit
not the sharpest tool in the box
slow-witted
not the sharpest tool in the shed
intellectually challenged
cerebrally challenged
unintellectualized
vacant
mindless
light-witted
vacuous
doltish
unastute
ungenius
mentally challenged
cloistered
fool
noninsightful
unskillful
sharp as a bowling ball
uninsightful
unknowledgeable
simple-mindedly
nonintellectual
subintellectual
uncleverness
unreasonably