(computing, programming) A built-in function that is implemented directly by the compiler, without any intermediate call to a library.

(video games) An ability possessed by a character and not requiring any external equipment.

Innate, inherent, inseparable from the thing itself, essential.

(anatomy, of a body part) Situated, produced, secreted in, or coming from inside an organ, tissue, muscle or member.

(programming, of a function or operator) Built-in.