predefined function
Computing term for a function already defined in a library or language, ready to be called without additional user definition.
Python provides many predefined functions.
Using predefined functions allows you to write shorter code.
組み込み関数 (built-in function) is a subset of predefined functions that are part of the language core, while 定義済み関数 can include functions from any library.
Compound of 定義 (definition) + 済み (done, already) + 関数 (function). A straightforward technical term.