騎兩輪車的人
兩個意思其實是同一個畫面，差別只在車上有沒有引擎。英文沒有為這兩種人分出不同的字，所以要靠場景來讀。
noun · B1
Someone who rides a motorcycle, especially someone who rides together with a group of others and makes motorcycles a big part of their life and their look.
機車騎士／重機族
核心畫面
You can picture someone sitting across two wheels, with the machine under them acting as their label. Biker does not first tell you where the person is going. It tells you what they ride, and often who they ride with. So the same word can show you a loud line of motorcycles on a mountain road, or a person pushing pedals along a river path.
可以想成一個人跨坐在兩個輪子上，身下那台車就是他的標記。biker 先講的不是他要去哪裡，而是他騎的是什麼、跟誰一起…更多收起
可以想成一個人跨坐在兩個輪子上，身下那台車就是他的標記。biker 先講的不是他要去哪裡，而是他騎的是什麼、跟誰一起騎。所以同樣一個字，畫面可能是山路上轟隆隆的一排重機，也可能是河濱步道上踩著踏板的人。From the word’s history
Bike is a shortened form of bicycle, from bi- (two) plus cycle (wheel, circle). The ending -er names the person who does it, so biker lands on the person on two wheels.
bike 是 bicycle 剪短來的，bicycle 是 bi-（二）加上 cycle（輪子、圈）；字尾 -er 指「做這件事的人」。合起來就落在「騎兩個輪子的人」這個畫面上，後來引擎裝上去了，字沒有改。
Wiktionary etymology tree supplied in packet (kaikki:3f6f69a190036ae4:702603790:25936): bi- + cycle > bicycle > bike; -er from Old English -ere.
One branch