- 1鐵路幹線；主線。
A main-line is the important railway that joins two cities, the one the fast trains use. Smaller tracks that leave it for towns along the way are branch lines. You will see it written as two words (main line) just as often, and with a when it describes something: a main-line train, a main-line station. Though actually, Americans more often write main line as two words for the railway, and they also use Main Line as a place name for a string of rich towns near Philadelphia — that is not this sense. There is also a slang verb mainline, to put a drug straight into the blood; that is a different world, and you do not need it to understand the train.
main-line 指連接兩座城市的重要鐵路，也就是快車通常走的那條。從幹線分出去、通往沿途小鎮的較小路線，叫做支線。這個字寫成兩個字也很常見，當它用來修飾東西時會加連字號，例如「a main-line train」和「a main-line station」，分別是幹線列車和幹線車站。
美國人也用 Main Line 指費城附近一帶富裕的小鎮，那是地名，不是這個意思。另外還有一個跟毒品有關的俚語動詞，和火車無關，理解這個字時可以先放下。
組成From main + line. Main is the chief or most important one; line is the railway route.
原始詞典資料1 筆記錄
以下是外部詞典記錄的用法，摘錄並精簡格式，我們還沒有寫成教學內容。上面的說明才是我們自己寫的；有些用法可能上面已經講過了。
這個拼法也被記錄為下列字的變化形：
摘錄自 英文維基詞典 English Wiktionary，已精簡格式；依 CC BY-SA 4.0 授權使用，改動後的內容同樣以此授權提供。