dumb as a rock
Utterly without intelligence
Dumb as a rock describes someone or something utterly stupid, emphasizing complete lack of intelligence or awareness.
Rocks, being inanimate, represent the lowest possible baseline for mental capacity: He's dumb as a rock, but he means well.
The phrase is insulting but often used with exasperated affection.
- foolishLacking good sense
- ignorantLacking knowledge or awareness
- simplemindedLacking mental acuity
- brainlessDevoid of intelligence
- inaneLacking sense or meaning
witless · vacuous · sharp as a marble · dull-witted · wooden-headed · senseless · dim bulb · not the brightest bulb · obtuse · stupid · blockhead · unintelligent · not the sharpest tool in the shed · thick as a brick · slow on the uptake · birdbrain · clueless · lights are on but nobody's home
- Smartsintelligent, genius, smart, gifted, brilliant
dumb as a rockbrilliant
Intensely bright or gifted
genius · smart as a whip · sharp as a tack · Einstein · intellectual
dumb as a rockquick-witted
Fast at thinking
quick on the uptake · sharp as a tack · sharp · astute · keen
dumb, dumber, dumbest, dumbly, dumbness, dumbed, dumbing, rock, rocks