Meaning of linchpin

linch•pin

Pronunciation: (linch'pin"), [key]
— n.
  1. a pin inserted through the end of an axletree to keep the wheel on.
  2. something that holds the various elements of a complicated structure together: The monarchy was the linchpin of the nation's traditions and society.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.
See also: