If something is extrinsic, it comes from outside — it is not part of the thing itself, and often it is not even close to the heart of it. The word you will meet most is in school and psychology: extrinsic motivation. That means you work because you want a prize, a grade, money, or someone's praise. The push sits outside you. The pair word is intrinsic: you do it because the thing itself matters to you. Doctors use extrinsic for a cause that does not start in the body; lawyers use it for a fact that is not really about the case. It is a formal, classroom word. On the street people just say outside or external. Though actually, speakers stretch it: any outside pressure gets called extrinsic, even when a simpler word would do. It is not a daily-life word, and using it in a chat can sound like you have swallowed a textbook.