Definition

In a way that is deceitful and untrustworthy, often betraying someone's trust.

Example

He perfidiously revealed their secrets to the enemy.

Conversation

Did you hear about how he acted so perfidiously during the game?

Yeah, I was shocked! I thought he was a team player.

It’s disappointing when someone behaves perfidiously like that.

Totally! It ruins the spirit of teamwork.

Synonyms & Antonyms

Root Explanation

Perfidiously → It is formed from "perfidus" (from Latin, meaning treacherous or deceitful) and the suffix "-ly" (meaning in a manner of). The word "perfidiously" means in a treacherous or deceitful manner.

Memory Tip

Think of someone acting in a 'treacherous' way ('perfidus') — that's why 'perfidiously' means doing something deceitfully.

Visually Confused Words