Definition of sharp as a tack in US English:

sharp as a tack


North American
  • Extremely clever or astute.

    • ‘She was a brilliant speed player, sharp as a tack.’
    • ‘As a lawyer in Southern California with a mind that's sharp as a tack, it's not good to miss even one day (she's mega-prolific) of her blog.’
    • ‘It should be noted that his mind is sharp as a tack.’
    • ‘Cassandra is sharp as a tack, awkward, and still young enough to greet her awakening desire and finer perceptions with astonishment and hyperbole.’
    • ‘This guy's as sharp as a tack and I respect his opinions immensely.’
    • ‘She's a bit too bossy, but she's also as sharp as a tack.’
    • ‘She may have been old, but she was as sharp as a tack.’
    • ‘She'd been vocal in class discussions and sharp as a tack.’
    • ‘But he was a loyal lieutenant to our ultimate boss, a genial man with a mind as sharp as a tack and a consummate skill at getting people to agree with each other, known to everyone as ‘Jack’.’
    • ‘She's a lovely 77-year-old woman, sharp as a tack, without an enemy in the world.’