vacant
mindless
vacuous
vacancy
stupid
unintelligent
lackluster
underbrained
unintelligence
shallowness
superficiality
shallow
simplicity
pedestrian
simple
not the sharpest tool in the box
not the sharpest knife in the drawer
simpleton
earthbound
stupidass
prosaic
incogitancy
prosy
not the sharpest tool in the shed
imaginationless
obtuse
purblind
gormless
underimagined
clueless
acognitive
simple-mindedly
nonintelligent
mental block
nonintellectual
thoughtless
brute
nonintelligence
unknowledgeable
unimaginativeness
unbright
blockish
unwittingly
incognizant
myopia
unknowingly
inadvertently
foresightlessness
insensibility
dim