Two sides at each other from opposite directions. Where their lines of fire cross there is a patch of ground that belongs to neither side, and whatever stands in it is reached from both directions at once. The word names that patch — which is why it is nearly always said about the person in the middle, not about the people shooting.
可以想成兩邊互相開火，兩條火線在中間交叉成一個 X。那個交叉的地方不屬於任何一邊，站在裡面的人兩邊都躲不掉。crossfire 指的就是那塊地方，所以這個字幾乎都是從「中間那個人」的角度說出來的，而不是從開槍的人。
From the word’s history
The word is literally cross- plus fire: fire that crosses. The modern meaning has stayed on that crossing point.
字面就是 cross-（交叉）加 fire（開火）：交叉的火力。這條線索和今天的用法對得很準——這個字從頭到尾講的都是「火線交會的那一塊」。
Wiktionary (kaikki extract, source_ref kaikki:3f6f69a190036ae4:1340946868:16117): 'From cross- + fire.'
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