sharp as a tack
Keenly quick-witted
Sharp as a tack means highly intelligent, mentally quick, or keenly perceptive.
The comparison is to the pointed end of a tack—small but piercing.
The phrase often emphasizes surprising mental acuity, especially in the elderly: She's ninety-two and still sharp as a tack.
Intensely bright or gifted
- astuteMentally sharp, discerning
- cleverShowing mental quickness
- quick-wittedFast at thinking
- shrewdPractically clever, perceptive
smart · brainy · savvy · perceptive · insightful · cerebral · analytical · canny
Causing amusement or laughter
- cleverShowing mental quickness
- quickMoving with speed
- banterPlayful, teasing exchange
- quipBrief, clever remark
repartee · sardonic · droll · satirical · ironic · puns · jest · sarcastic
Paying close notice
- observantNoticing things readily
- keenSharp or enthusiastic
- awareHaving knowledge of
- watchfulCarefully attentive, observant
vigilant · on the ball · quick · responsive · clear-headed · focused · present · awake
brilliant
Intensely bright or gifted
- astuteMentally sharp, discerning
- cleverShowing mental quickness
- quick-wittedFast at thinking
shrewd · smart · brainy · savvy · perceptive · insightful · cerebral · analytical · canny · perspicacious
humorous
Causing amusement or laughter
quip · repartee · sardonic · droll · satirical · ironic · puns · jest · sarcastic · facetious
attentive
Paying close notice
watchful · vigilant · on the ball · quick · responsive · clear-headed · focused · present · awake · tuned in
- folk sayingsproverb, adage, maxim, folk saying, old saying
- Mind Idiomsopen mind, quick wit, bird brain, pea brain, big brain
- skill idiomsknow the ropes, cut the mustard, on the ball, jack of all trades, hit the ground running
- Smartsintelligent, genius, smart, gifted, brilliant
- appearance idiomsall dolled up, dolled up, done up, dressed to kill, dressed to the nines
- Precision phraseson the mark, on target, spot on, dead on, bulls-eye
sharp as a tackthick as a brick
Hopelessly slow mentally
dull · stupid · dense · slow-witted · dim-witted
sharp, tack, sharpen, sharper, sharpness, sharply, sharpened, sharpest, sharpish