Pronunciation: (mag-nē'tu-pôz"), [key]
1. the boundary between the earth's magnetosphere and interplanetary space, ab. 40,000 mi. (65,000 km) above the earth, marked by an abrupt decrease in the earth's magnetic induction.
2. a similar feature of some other planet.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.