Anti-grav
From Memory Alpha, the free Star Trek reference.
An anti-grav is any device capable of nullifying the force of gravity, usually to lift loads of an extremely high mass. Anti-grav devices were in use primarily during the 23rd century.
At various times these devices were used to transport Nomad, to handle an anti-matter bomb, and later to carry the Medusan Ambassador Kollos around the USS Enterprise. (TOS: "The Changeling", "Obsession", "Is There in Truth No Beauty?") The unit Captain Kirk and Ensign Garrovick used to transport the anti-matter bomb was marked ANTI-GRAV 57,000 Gkg. (TOS: "Obsession")
By the 24th century, these devices were upgraded into the larger anti-grav sled. Wheelchairs using anti-grav units were also available.
