stropyoudaoicibaDictYouDict[strop 词源字典]
strop: [OE] Strop has now narrowed down in meaning to the specialized ‘strip of leather for sharpening a razor’, but it used to be a much more general term for a leather band or loop. It goes back to a prehistoric West Germanic word that was probably an adoption of Latin stroppus ‘strap, band’. That in turn may well have come from Greek strophos ‘twisted band’, from strephein ‘turn’.

Old French had estrope from the same West Germanic source, and that probably reinforced the English word in the 14th century. Scottish pronunciation turned strop into strap [17], and that has now inherited most of the general functions of strop in English at large. As for stroppy ‘bad-tempered and uncooperative’, first recorded in 1951, no convincing link with strop ‘leather strip’ has ever been established (strop ‘fit of stroppiness’ is a back-formation from stroppy).

One suggestion is that it may be a radically stripped-down version of obstreperous.
[strop etymology, strop origin, 英语词源]
strop (n.)youdaoicibaDictYouDict
mid-14c., "loop or strap on a harness," probably from Old French estrop, making it the older and more correct form of strap (n.), replaced by it from 16c. Specific sense of "leather strap used for sharpening razors" first recorded 1702. The verb in this sense is from 1841. Related: Stropped; stropping. Distribution of senses between strap and strop is arbitrary.