Meaning of the word "a nail in the coffin" in English

What does "a nail in the coffin" mean in English? Explore the meaning, pronunciation, and specific usage of this word with Lingoland.

a nail in the coffin

US /ə neɪl ɪn ðə ˈkɔfɪn/
UK /ə neɪl ɪn ðə ˈkɒfɪn/

Idiom

an action or event that causes the failure or destruction of something

Example:
The company's latest scandal was a nail in the coffin for its reputation.
His decision to quit was a nail in the coffin for the struggling project.