Megalight

MGLT (which is believed to stand for 'Micro-Gravity Linear [Acceleration] Tolerance') is a measurement of acceleration.

MGLT is roughly equivalent to a rate of acceleration of approximately 400 meters per second² (m/s² or "meters per second" per second).

It is used to measure the rate at which the ion thrusters of a vessel can increase the absolute speed of a vessel in a micro gravity environment such as the vaccuum of space.

External Sources
http://www.theforce.net/swtc/units.html