treadle (n.)youdaoicibaDictYouDict[treadle 词源字典]
"lever worked by foot," c. 1400, from Old English tredel "step, stair, sole of the foot," from tredan "to tread" (see tread (v.)) + instrumental suffix -el (1). Compare handle (n.).[treadle etymology, treadle origin, 英语词源]