King James Bible Dictionary

TREACHEROUSLY, adverb trech'erously. By violating allegiance or faith pledged; by betraying a trust; faithlessly; perfidiously; as, to surrender a fort to an enemy treacherously; to disclose a secret treacherously

You treacherously practic'd to undo me.

TREACHEROUSNESS, noun trech'erousness. Breach of allegiance or of faith; faithlessness; perfidiousness.

General references
Jeremiah 9:8

Of Rahab to her people
Jeremiah 6:2

Of the man of Beth-El
Judges 1:24-25

Of Jael
Judges 4:18-21

Of Shechemites
Judges 9:23

Of Joab
2 Samuel 3:26-27

Of Baanah and Rechab
2 Samuel 4:6

Of David to Uriah
2 Samuel 10:11

Of Joab to Amasa
2 Samuel 20:9-10

Of Jehu
2 Kings 10:18-28

Of the enemies of Nehemiah
2 Kings 16:6
Conspiracy; Treason

TREACHERY, noun trech'ery. Violation of allegiance or of faith and confidence. The man who betrays his country in any manner, violates his allegiance, and is guilty of treachery This is treason. The man who violates his faith pledged to his friend, or betrays a trust in which a promise of fidelity is implied, is guilty of treachery The disclosure of a secret committed to one in confidence, is treachery This is perfidy.