Entity and Quiddity

Entity noun - One that has a real and independent existence.

Quiddity is a synonym for entity in essential nature topic. In some cases you can use "Quiddity" instead a noun "Entity", when it comes to topics like nature of a being.

Quiddity noun - An odd or peculiar habit.

Entity is a synonym for quiddity in heart topic. You can use "Entity" instead a noun "Quiddity".