A government's policy of staying out — deliberately not stepping into another country's troubles, even when it could. If a civil war breaks out somewhere and other countries decide not to send soldiers, not to arm either side, and not to try to change who wins, that is a policy of non-intervention.

The key word is "policy". This is not simply doing nothing because you are far away or busy. It is a chosen position, often argued for openly: that every country has the right to settle its own affairs, and that outsiders who march in usually make things worse. It is a formal, political word — you meet it in newspapers, history classes, and speeches, not in conversation.

It carries a certain weight because history has judged it both ways. Non-intervention has been praised as respect for other people's independence, and attacked as a polite name for standing by while people are killed. When someone uses the word, listen for which way they lean; the word itself is neutral, but almost nobody uses it neutrally.

Outside politics you sometimes hear it more loosely — a doctor's policy of non-intervention means letting the body heal on its own instead of operating, and a parent might describe their approach to a children's quarrel that way. But the political sense is the main one.