Is it ensure, insure, or assure?
condition experienced while in free-fall (q.v.), in which the effect of gravity is canceled by the inertial (e.g., centrifugal) force resulting from orbital flight. The term zero gravity is often used to describe such a condition. Excluding spaceflight, true weightlessness can be experienced only briefly, as in an airplane following a ballistic (i.e., parabolic) path