A firth is a long, narrow arm of the sea that reaches in between two pieces of land — often the wide mouth of a river where it opens out and meets the ocean.

A firthfirth is a long, narrow arm of the sea是一條又長又窄的海灣（海水伸進陸地間的部分）that reaches in between two pieces of land伸進兩塊陸地之間——often the wide mouth of a river where it opens out and meets the ocean通常是河流出海變寬、和海洋相接的那個河口。

The word belongs to Scotland. You meet it mainly in place names on a map: the Firth of Forth, the Firth of Clyde, the Moray Firth. Outside Scotland almost nobody uses it as an ordinary word, and even in Scotland people usually say it as part of a name rather than saying 'let us go and look at a firth'.

The word這個字belongs to Scotland是蘇格蘭特有的。You meet it mainly in place names on a map你主要會在地圖上的地名裡碰到它：the Firth of Forth, the Firth of Clyde, the Moray Firth像是the Firth of Forth、the Firth of Clyde、the Moray Firth。Outside Scotland almost nobody uses it as an ordinary word蘇格蘭以外幾乎沒人把它當一般的字來用，and even in Scotland people usually say it as part of a name而且就算在蘇格蘭，大家通常也是把它當成地名的一部分來說，rather than saying 'let us go and look at a firth'而不會說『let us go and look at a firth（我們去看個firth吧）』。

So how does it differ from a bay? A bay is wide and open; a firth is long and narrow, squeezed between land on both sides, and the sea reaches quite far inland.

So how does it differ from a bay那它跟bay（海灣）有什麼不一樣呢？A bay is wide and openbay是寬闊開放的；a firth is long and narrowfirth則是又長又窄，squeezed between land on both sides被兩邊的陸地夾住，and the sea reaches quite far inland而且海水會深入內陸很遠。

And here is the useful connection: firth is the same word as fjord, the Norwegian word for those steep narrow sea inlets. Both came from the same old northern root, one through Norse into Scots, one straight from Norwegian. Scotland's coast has them for the same reason Norway does — ice carved the land.

And here is the useful connection這裡有個有用的關聯：firth is the same word as fjordfirth跟fjord其實是同一個字，the Norwegian word for those steep narrow sea inletsfjord是挪威語裡形容那種陡峭狹窄海灣的字。Both came from the same old northern root兩個字都來自同一個古老的北方字根，one through Norse into Scots一個經過古諾斯語進入蘇格蘭語，one straight from Norwegian一個則直接來自挪威語。Scotland's coast has them for the same reason Norway does蘇格蘭海岸會有這種地形，原因跟挪威一樣——ice carved the land是冰河刻出來的。

For a student, this is really a reading word. You need it to understand a map, a news story about a Scottish bridge, or a novel set in the north. You will almost never need to write it.

For a student對學生來說，this is really a reading word這其實是個閱讀用的字。You need it to understand a map你需要它來看懂地圖、a news story about a Scottish bridge一篇關於蘇格蘭某座橋的新聞，or a novel set in the north或一本背景在北方的小說。You will almost never need to write it你幾乎不會需要自己寫出這個字。