LY, light year - The distance travelled by light in one year. Light travels at 300,000 km/sec, so a lighty year is 1 light year = 9.4605284 × 1015 meters. light second - 300,000 km or the distance light travels in one second  FTL - faster than light.  FTL drive -the drive that enables ships to cross interstellar distances fast than light would (so in a relatively short time)