Definition of at a (or one) whack in US English:

at a (or one) whack

phrase

informal
  • At one time.

    ‘he built twenty houses at one whack’
    • ‘The three men were from Florida and are hiking the AT in sections, knocking out the trail a week at a whack twice a year.’
    • ‘And since they leave me in these little rooms for half-an hour at a whack, I could have plenty of time.’
    • ‘I usually load a ship six months at a whack with 8,000 pounds of meat.’
    • ‘For example, taking off with skeevy men for 45 minutes at a whack, as I waited on grouchy after-workers, answered the telephone and tried to find where Frank had hidden people's clothes.’
    • ‘What all of these engine and fuel numbers come down to is that the T - 38 can fly for about 2 hours at a whack.’
    • ‘When you watch a movie it plays for two hours or more at a whack, and the players are designed to play movies many, many times!’
    • ‘Unfortunately we're stuck on hold for 5 minutes at a whack because these sites aren't on the allowed list.’
    • ‘I am on board the U.S. Coast Guard icebreaker Polar Star as it back-and-rams the frozen ocean to open up a fourteen-mile-long channel into McMurdo Station, fifty feet at a whack.’
    • ‘The basic premise was that we would commence with a 24-inch barrel, test for accuracy and velocity, and then shorten it two inches at a whack before repeating our testing.’
    • ‘After he kills ten yellow jackets at a whack, Jack is recruited for killing some animals that are terrorizing a town.’