ungenius
lackluster
nongenius
uninventiveness
lackbrain
unintelligence
cerebrally challenged
intellectually challenged
inexpertness
nonvisionary
unvisionary
vacancy
unintelligent
nonintelligent
nondiligence
unskillfulness
dull
subexpert
unproficiency
improficiency
inexpertise
nonproficiency
unknowledgeable
uncreativeness
inadequacy
unskilfulness
skillessness
untalented
underbrained
simplicity
dim
mentally challenged
unbright
unbrilliant
nontalent
unimaginativeness
half-witted
outskilled
lusterless
unskill
unartful
unworldly
inaptitude
underwitted
blockish
unsophisticated
ham-fisted
gormless
unskillful
drool bucket
ungifted
stun
talentlessness
inadept
divvie
monosynaptic
pinheaded
dense
doltish
incompetent
not the sharpest tool in the shed
underproficient
bungling
nonenmity
underimagined
fumbling
halfwit
nontalented
not the sharpest tool in the box
stewpot
clumsy
not the sharpest knife in the drawer
midget-minded
dropkick
uneducation
untutoredness
dyscompetence
shtus
stupid
insufficiency
unscholarlike
stockishness
worse
dunderheadism
numskullery
brain damage
nonmastery
thickheadedness
incogitancy
dunderheadedness
incapacity
unvalorous
unastute
light-witted