unicycle
n.
1869, American English, from Latin uni- "one" (see uni-) + -cycle, from bicycle (from Greek kyklos "circle, wheel").
〔蒋〕[uni单一，独，cycl轮] 独轮脚踏车
〔李〕[un=one 一；-i-; cycl=circle 圆环；-e→“one-circled vehicle一个轮的车”→] n. one-wheeled vehicle used by acrobats（杂技演员用的）独轮车