peg (n.)youdaoicibaDictYouDict[peg 词源字典]
mid-15c., from Middle Dutch pegge "peg," a common Low German word (Low German pigge "peg," German Pegel "gauge rod, watermark," Middle Dutch pegel "little knob used as a mark," Dutch peil "gauge, watermark, standard"), of uncertain origin; perhaps from PIE *bak- "staff used as support" (see bacillus). To be a square peg in a round hole "be inappropriate for one's situation" is attested from 1836; to take someone down a peg is from 1580s, but the original literal sense is uncertain (most of the likely candidates are not attested until centuries later). Peg leg "wooden leg" attested from 1765.[peg etymology, peg origin, 英语词源]
peg (v.)youdaoicibaDictYouDict
"fasten with or as if on a peg," 1590s, from peg (n.). Slang sense of "identify, classify" first recorded 1920. Related: Pegged; pegging.