A person who jumps out of an airplane with a parachute and falls through the air before opening it to land safely.
From sky (from Old English 'sceo', cloud) + dive (from Middle English 'diven', to plunge) + -er (agent noun). Skydiving was invented in the 1920s-30s.
Skydivers experience weightlessness without being in space — they're actually in free fall the whole time, and so is the plane they jumped from, but they're falling at slightly different speeds because of air resistance.
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