Definition

Not being loyal or true to someone or something, especially in a relationship or commitment.

Example

He was unfaithful to his partner, which led to the end of their relationship.

Conversation

I heard that Mark was being unfaithful to his girlfriend.

Really? That’s surprising; I thought he was committed to her.

Yeah, it’s disappointing to see someone so unfaithful in a relationship.

Absolutely, trust is really important in any partnership.

Synonyms & Antonyms

Root Explanation

Unfaithful → It is formed from "un-" (meaning not) and "faithful" (from Old English "fæth" meaning faith or trust, combined with "-ful" meaning full of). The word "unfaithful" means not full of faith or trust, indicating a lack of loyalty or fidelity.

Memory Tip

Think of 'not' ('un-') being added to 'full of faith' ('faithful') — that's why unfaithful means lacking loyalty or trust.

Visually Confused Words