The Collaborative International Dictionary of English v.0.48:

Buggy \Bug"gy\, n.; pl. Buggies.
   1. A light one horse two-wheeled vehicle. [Eng.]
      [1913 Webster]

            Villebeck prevailed upon Flora to drive with him to
            the race in a buggy.                  --Beaconsfield.
      [1913 Webster]

   2. A light, four-wheeled vehicle, usually with one seat, and
      with or without a calash top. [U.S.]
      [1913 Webster]

   Buggy cultivator, a cultivator with a seat for the driver.


   Buggy plow, a plow, or set of plows, having a seat for the
      driver; -- called also sulky plow.
      [1913 Webster]