Parsec

A parsec was a unit used to measure distance. It was used by the Time Lords. (TV: The Ribos Operation) After landing on Karn, the Fourth Doctor claimed that the Time Lords had drug the TARDIS 1000 parsecs off course. (TV: The Brain of Morbius)

Behind the scenes
In the real world, the parsec is a unit of length used in astronomy, equal to about 30.9 trillion kilometres (19.2 trillion miles) or 3.26 light-years.