perfidious

adjective. disloyal, adulterous

Word Origin & History

1590s, from Latin perfidiosus "treacherous," from perfidia (see perfidy). Related: Perfidiously; perfidiousness.

All is lost, for the sake of that inveigling, perfidious young Syren.

The czarina was strong-minded, but neither cruel nor perfidious.

The sea is a perfidious element, but what is it to the blind malevolence of men?

An English poet has said of woman, 'Perfidious as the waves,' my son.

On one was a satire on the hypocritical rapacity of perfidious Albion.

But thou, detestable Nicias, thou art but a perfidious venom and a bitter poison.

He is an agent of perfidious Normandy; he is under the pay of foreigners.

The perfidious wretches then rushed forward, with gleaming knives.

This she said in French and in German, and in her own perfidious tongue.

This is the reason that perfidious girl so boldly took his part!