nonintelligence
underbrained
vacancy
unintelligence
stupid
unintelligent
stupidass
not the sharpest tool in the shed
not the sharpest tool in the box
not the sharpest knife in the drawer
gormless
untutoredness
uneducation
lackluster
vacant
mentally challenged
mindless
vacuous
weak
indocible
cerebrally challenged
inexpertise
intellectually challenged
shallow
nonintelligent
simpleton
incapacity
simple-mindedly
simple
cerebricity
dense
slow
halfwit
ignorance
clueless
nonintellectual
unlettered
unlearned
unlearnedness
nescient
ignorant
dysrationalia
dimwit
sophomania
insightlessness
unskillfulness
uncultivated
lowbrow
anti-intellectual
philistine