Zero Gravity: A term often used to describe the complete absence of gravitational force. It is not entirely accurate since gravitational forces are still present but significantly reduced in microgravity.
Freefall: The state of an object or person moving under the sole influence of gravity with no other forces acting upon it. Astronauts in orbit around Earth are essentially in a continuous state of freefall.
Space Adaptation Syndrome (SAS): A collection of symptoms experienced by some individuals during their transition from Earth's gravity to microgravity. Symptoms can include nausea, dizziness, and disorientation.