six \six\, n.
   1. the number greater by a unit than five; the sum of three
      and three; six units or objects.
      1913 webster

   2. a symbol representing six units, as 6, vi., or vi.
      1913 webster

   to be at six and seven or to be at sixes and sevens,
      a to be in disorder. --bacon. --shak. --swift.
      b to be in a dispute or disagreement; -- often used with
          with.
          1913 webster +pjc
see also:
to be at six and seven to be at sixes and sevens