Aircraft that are lighter-than-air are typically associated with dirigibles, blimps, and airships. However, there are many different synonyms that can be used to describe these machines. Some of the most common alternatives include aerostats, balloon aircraft, buoyant aircraft, and gas-filled aircraft. Additionally, many lighter-than-air machines share similarities with helicopters or other rotary aircraft, meaning that terms like rotary-wing airships, aerodynes, or rotorcraft may also be applicable. Ultimately, the specific word used to describe a lighter-than-air machine will depend on its size, shape, and function, as well as the context in which it is being discussed.