built-in
adjectiveUK /ˌbɪltˈɪn/
US /ˌbɪltˈɪn/
Something built-in is made as a part of something else and cannot be taken out.
My new backpack has a built-in water bottle holder.
OTHER MEANINGS
2. A feature that comes with a product from the start.
The phone's built-in camera takes great pictures.
3. Something that is a natural part of a person or thing.
She has a built-in sense of fairness.
4. In computing, a function that is already part of a programming language.
The built-in function sorts the list for you.