However, "heart" is often used in idiomatic expressions, which are phrases with a figurative meaning that differs from the literal meaning of the individual words.
Here are some examples of idioms using "heart":
* "Have a heart": To be kind and compassionate.
* "Break someone's heart": To cause great emotional pain.
* "Put your heart into it": To do something with great effort and enthusiasm.
* "Have your heart set on something": To strongly desire something.
* "Follow your heart": To make decisions based on your emotions and desires.
* "Learn something by heart": To memorize something completely.
* "Heart of gold": A kind and generous person.
* "Get to the heart of the matter": To understand the most important part of a situation.
So, while "heart" itself is not an idiom, it's a very common word used in many idiomatic expressions.