sharp as a marble
- dullLacking edge or interest
- denseClosely packed together
- dimLow in light
- slowLacking in speed
- obtuseLacking mental sharpness
thick · witless · clueless · dopey · numbskull · brick · doorknob · rock · sarcasm · irony · idiot · fool · simpleton · blockhead · dunce · oxymoron · contradiction · humor
intelligence/mental acuity
sharp as a marblebrilliant
Intensely bright or gifted
sharp as a tack · genius · intelligent · bright · smart as a whip
idiomatic irony
sharp as a marblesharp as a tack
Extremely intelligent and alert
smart as a whip · bright as a button · wise as an owl · smart cookie · nobody's fool