Meaning of petit treason

pet'it trea'son

Pronunciation: (pet'ē), [key]
— Eng. Law. Eng. Law.
  1. the killing of a husband by his wife, of a lord by his servant, or of an ecclesiastic by a subordinate ecclesiastic.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.