locking piece: Meaning and Definition of

lock'ing piece"

Pronunciation: [key]
— Horol. Horol.
  1. (in a striking train) a hooked part, rising and falling on a locking plate and arresting the rotation of the plate after the proper number of strokes.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.