The hoverchair is a terran device that utilizes anti-gravity technology. It is used by those who are physically disabled, namely the lack of use of their legs.
A variant of the hoverchair exists in the form of the convalchair, which is used for medical purposes.
References
DeCandido, Keith R. A. (November 28, 2006). StarCraft: Ghost: Nova. Simon & Schuster (Pocket Star). ISBN 0-7434-7134-2