treachery Meaning, Definition & Usage

  1. noun betrayal of a trust
    perfidy; perfidiousness.
  2. noun an act of deliberate betrayal
    perfidy; betrayal; treason.

WordNet

Treach"er*y noun
Etymology
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.
Definitions
  1. 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.

Webster 1913