treachery

As a verb renege

is to break a promise or commitment; to go back on one's word.

As a noun treachery is

deliberate, often calculated, disregard for trust or faith.

As a noun treachery

is deliberate, often calculated, disregard for trust or faith.

As an adjective perilous is

dangerous, full of peril.

As nouns the difference between treachery and deception

is that treachery is deliberate, often calculated, disregard for trust or faith while deception is disappointment.

As nouns the difference between treachery and hearsay

is that treachery is deliberate, often calculated, disregard for trust or faith while hearsay is information that was heard by one person about another.

As nouns the difference between treachery and infidelity

is that treachery is deliberate, often calculated, disregard for trust or faith while infidelity is unfaithfulness in marriage: practice or instance of having a sexual or romantic affair with someone other than one's spouse, without the consent of the spouse.

As a noun treachery

is deliberate, often calculated, disregard for trust or faith.

As an adjective undefined is

lacking a definition or value.

As nouns the difference between treasury and treachery

is that treasury is a place where treasure is stored safely while treachery is deliberate, often calculated, disregard for trust or faith.

As nouns the difference between insidiousness and treachery

is that insidiousness is a surreptitious harmfulness, quality of entrapment, or treacherousness; the characteristic of being insidious while treachery is deliberate, often calculated, disregard for trust or faith.

As nouns the difference between loyalty and treachery

is that loyalty is the state of being loyal; fidelity while treachery is deliberate, often calculated, disregard for trust or faith.

As a noun treachery

is deliberate, often calculated, disregard for trust or faith.

As an adjective perfidious is

of, pertaining to, or representing perfidy; disloyal to what should command one's fidelity or allegiance.