Meaning of the word "to the core" in English

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

to the core

US /tə ðə kɔr/
UK /tə ðə kɔː/
"to the core" picture

Idiom

completely; thoroughly; to the greatest extent

Example:
He was rotten to the core.
She was a New Yorker to the core.
Related Word: