Cosmeg

noun
A single star containing all the mass in the universe.
Origin
Abbreviated from ‘cosmic egg’.
Source
The Gods Themselves

Agrav

noun
A material producing an anti-gravity effect.
Source
A Fire Upon the Deep

Spindizzy

noun informal
The Dillon-Wagoner gravitron polarity generator, an anti-gravity device that also enables faster-than-light travel.
Origin
Named for the device’s effect on the magnetic moment of atoms within its field.
Source
Cities in Flight