D defs.my
Entry 2 senses Webster, 1913

Aërostat

· A·ër·o·stat · IPA
01 n. A balloon, especially a passive balloon; a balloon without motive power. Contrasted with aerodyne.
  1. 1.
    A balloon, especially a passive balloon; a balloon without motive power. Contrasted with aerodyne.(Aëronautics) See: aerodyne
  2. 2.
    A balloonist; an aëronaut.