Deliberate, often calculated, disregard for trust or faith. (noun)
The act of violating the confidence of another, usually for personal gain. (noun)
Examples of word treachery
This determined man, whose experience in the East Indies was of long date, and who had already served as director-general, came into his new office with an intense prejudice against the English, and with a firm resolve to put an end to what he described as their treachery and intrigues.
In this condition the legions burst in on them, furious at what they called the treachery of the previous day, and merciless in their vengeance.
Fink grumbled, and Anton could not forget what he called treachery to Bernhard; and so it was, that for some weeks they no longer spent their evenings together.
Of course, he was in a great rage at what he called the treachery of
Many, I believe, sense a terrible treachery is being perpetuated whilst being to busy to follow its awful details.