Peg
late Middle English: probably of Low German origin; compare with Dutch dialect peg ‘plug, peg’. The verb dates from the mid 16th century.
wiktionary
From Middle English pegge, from Middle Dutch pegge(“pin, peg”), from Old Saxon *pigg-, *pegg-, from Proto-Germanic *pig-, *pag-(“peg, stake”), from Proto-Indo-European *bak-, *baḱ-(“club, pointed stick, peg”). Cognate with Dutch dialectal peg(“pin”), Low German pig, pigge(“peg, stick with a point”), Low German pegel(“post, stake”), Swedish pigg(“tooth, spike”), Danish pig(“spike”), Norwegian Bokmål pigg(“spike”), Irish bac(“stick, crook”), Latin baculum(“staff”), Latvian bakstît(“to poke”), Ancient Greek βάκτρον(báktron, “staff, walking stick”). Related to beak.
This is one of the very few English words that begin with a p and come from Proto-Germanic. Proto-Germanic *p, when not in a consonant cluster beginning with *s, developed by Grimm's law from the Proto-Indo-European consonant *b, which was very rare.
etymonline
peg (n.)
"pointed pin of wood, metal, or other material," mid-15c., pegge, from Middle Dutch pegge "peg," or a similar 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 (or the reverse) "be inappropriate for one's situation" is attested by 1836; to take someone down a peg "humble, lower the esteem of" is from 1580s, but the original literal sense is uncertain (most of the sensibly plausible candidates are not attested until centuries later). Peg leg "wooden leg of the simplest form" is attested from 1765.
peg (v.)
"fasten with or as if on a peg, drive pegs into for the purpose of fastening," 1590s, from peg (n.). Meaning "fix the market price" is by 1882. Slang sense of "identify, classify" is recorded by 1920. Related: Pegged; pegging.
