The state in which a body is falling freely under the influence of gravity, as in freefall parachuting(skydiving). The term weightless is normally used to describe a body in free fall in space.
In orbit, astronauts and spacecraft are still held by gravity and are in fact falling toward the Earth. Because of their speed (orbital velocity), the amount they fall toward the Earth just equals the amount the Earth's surface curves away; in effect they remain at the same height, apparently weightless.