aer·o·stat (âr'ō-stāt') n. An aircraft, especially a balloon or dirigible, deriving its lift from the buoyancy of surrounding air rather than from aerodynamic motion.
[French aérostat : Greek āero-, aero-; see aero- + Greek statos, standing; see stato-.] aer'o·stat'ic, aer'o·stat'i·cal adj.