Satellite
Definition
Any object orbiting a planet — the Moon is natural, while the thousands of human-made satellites handle GPS, weather, TV, and internet.
Unit: meters per second (m/s) for orbital velocity
Technical definition
A body in orbit around a larger mass, held by gravity while its tangential velocity keeps it in continuous free fall around the planet. Orbital velocity at radius r is v = √(GM/r); geostationary satellites orbit at ~35,786 km altitude with a 24-hour period.
Example
The International Space Station orbits at about 400 km altitude, circling Earth every 92 minutes at 7.66 km/s. Astronauts float not because there is 'no gravity' — gravity there is still ~90% of Earth's surface value — but because they are in continuous free fall.
Satellites do not hover above Earth or escape gravity — they are falling toward Earth constantly, but moving sideways so fast they keep missing it. And 'zero gravity' in orbit is a myth; it is more honestly called microgravity, and it comes from free fall, not from being far from Earth.