Perfidiously [adverb]

Taking advantage of his absence, they perfidiously vilified him to the king.

(Perfidiously to the Marchioness) Look out, you know he's becoming dangerous for you.

Perfidiously, they only sought time to regain their strength.

He had been perfidiously treated, and Albuquerque now, in 1511, appeared before the city to call the monarch to account.

This man entered into a conspiracy with the English, to betray to them the King to whom he had perfidiously sworn allegiance.

Thus we learned the dismal place to which your noble daughter had been so perfidiously ensnared.

But the Prefet's party had perfidiously made thirty of its most devoted adherents vote for Albert, so as to deceive the enemy.

For it was long believed that Delauney had admitted the people into the first court, and then had perfidiously shot them down.

On the testimony of his own letters it is clear he did not mind how tortuously and perfidiously he worked.

His mistress loved him as long as his money lasted; when he had no more to throw away upon her she perfidiously betrayed him.