Treachery

Treach"er*y (?), n. [OE. trecherïe, trichere, OF. trecherie, tricherie, F. tricherie trickery, from tricher to cheat, to trick, OF. trichier, trechier; probably of Teutonic origin. See Trickery, Trick.] Violation of allegiance or of faith and confidence; treasonable or perfidious conduct; perfidy; treason.

Be ware, ye lords, of their treachery.
Chaucer.

In the council chamber at Edinburgh, he had contracted a deep taint of treachery and corruption.
Macaulay.