Balloon, nonpowered, nonrigid, lighter-than-air craft consisting of a bulbous envelope that holds the lifting medium and a payload-carrying basket, or “gondola,” suspended below. Balloons may be captive (secured to the ground by a cable) or free-flying. Lift may be provided by a gas such as hydrogen or nonflammable helium or by heated air. Balloons are used in science (weather forecasting and astronomy), as well as for recreational purposes.
See also: Zeppelin, Ferdinand von.