軍隊越過界線
最字面的一支：那條線是真的邊界，越線的是軍隊。
noun · C1
A sudden, usually short attack in which armed forces cross into land that belongs to another country or group, without meaning to stay and hold it.
突入／侵入
核心畫面
One way to hold it: a line drawn on the ground, and something suddenly coming in across it from the other side. The word names that one movement inward — not the staying, not the going out again, just the crossing in.
可以想成地上畫了一條線，然後有東西突然從外面越過那條線進來。這個字指的就是「進來」那一下：不是留下來，也不是退出去，…更多收起
可以想成地上畫了一條線，然後有東西突然從外面越過那條線進來。這個字指的就是「進來」那一下：不是留下來，也不是退出去，而是跨過那條界線的動作本身。From the word’s history
From Middle English, borrowed from Old French, from Latin incursiō. The word came into English already meaning a running in upon someone, and the modern senses all keep that one inward movement.
從中古英文往前推，是借自古法文，再往前是拉丁文 incursiō。它進到英文時就帶著「衝進來」的意思，今天的每一個用法都還留著那個往內的方向。
Wiktionary entry supplied in this packet (source_ref kaikki:3f6f69a190036ae4:516053251), etymology_text: From Middle English, borrowed from Old French, from Latin incursiō.
Three branches
不受歡迎地闖進別人的地方
把地上的線換成一條看不見的界線：別人的私事、別人的市場、本來是陸地的地方。越線的動作沒變，只是換了場景。
noun · C1
The sudden arrival of a person or thing in a place or activity where it does not belong or has never been before, usually said when it is not welcome.
闖入／侵入
澳洲學校：讓外面的人進來
同樣是往內跨過校門這條線，但這一支把「不受歡迎」整個拿掉了，因為這裡的進來是學校自己請的。
noun · C1
In Australian schools: an event held inside the school, where visitors come in to teach, perform or show something to the students — the opposite of an excursion, where the students go out.
校內體驗活動（澳洲）