Meaning of the word "poison pen letter" in English

What does "poison pen letter" mean in English? Explore the meaning, pronunciation, and specific usage of this word with Lingoland.

poison pen letter

US /ˈpɔɪ.zən pɛn ˈlɛt.ər/
UK /ˈpɔɪ.zən pɛn ˈlɛt.ər/

Noun

an anonymous letter containing unpleasant, abusive, or slanderous statements about someone

Example:
The politician received a poison pen letter threatening to expose his past.
She was upset after reading the malicious poison pen letter.