self-originated

not-comparable

that has originated from itself

Japanese Meaning

自己発生した / 自己起源の

The self-originated melody echoed through the empty hall, surprising everyone who had assumed it was rehearsed.

自己発生した旋律が閑散としたホールに響き渡り、それが練習されたものだと考えていた人々を驚かせた。

Sense（1）

that has originated from itself

It is completely self-originated and self-sufficient in its functioning.