double-crossing vs perfidy

double-crossing and perfidy both are nouns.

Word	Noun	Adjective	Verb	Adverb
double-crossing	Yes	No	No	No
perfidy	Yes	No	No	No

As nouns, perfidy is a hypernym of double-crossing; that is, perfidy is a word with a broader meaning than double-crossing:

Other hypernyms of double-crossing include betrayal, treachery, treason.

double-crossing (noun)	perfidy (noun)
an act of betrayal	an act of deliberate betrayal
	betrayal of a trust