Water turning fast in one place, with a dip in the middle. Whatever comes close is carried round the edge first, and then pulled down. The important part is not only that it turns, but that things inside it cannot easily get out again.
whirlpool 的畫面可以想成：水在同一個地方一直打轉，中間凹下去像個洞。靠近的東西先被帶著繞圈，接著被往下吸。重點不只是「會轉」，而是「轉著轉著就出不來」。這個「被捲進去、脫不了身」的感覺，正好貫串了這個字後來的各種用法。
From the word’s history
The word is built from whirl (to turn round) plus pool (a body of water), through earlier forms whirlpoole and whirlpole; older English also had hwierfepōl for the same thing. The parts still describe the picture exactly: a pool of water that whirls.
這個字由 whirl（打轉）加 pool（一池水）組成，更早的形式是 whirlpoole、whirlpole，古英語另有 hwierfepōl 指同一件事。字面和現在的畫面幾乎重疊：一池會打轉的水。
Wiktionary entry for whirlpool, supplied in this packet (source_ref kaikki:3f6f69a190036ae4:845818657)
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