perfidy

 
Pronunciation: /ˈpəːfɪdi/

noun

[mass noun] literary
  • the state of being deceitful and untrustworthy: it was an example of his perfidy Hapsburg perfidy

Origin:

late 16th century: via French from Latin perfidia, from perfidus 'treacherous', based on per- 'to ill effect' + fides 'faith'