Pronunciation: (mid'kôrs", -kōrs"), [key]
1. the middle of a course.
2. Rocketry.the portion of a ballistic trajectory between the end of powered flight and the beginning of the reentry phase.
3. Aerospace.the portion of a space trajectory between leaving the earth's vicinity and arrival at the desired destination, as another planet.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.