Pimple

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Middle English: related to Old English piplian ‘break out in pustules’.

wiktionary

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Early Modern English pimple, pumple, from Middle English pymple, pympyl, of uncertain origin but probably a nasalized variant of Old English *pipel, *pypel, from Old English piplian, pyplian(“to break out in pimples, show eruptions”), probably related to Latin papula(“pimple, pustule”) (from Proto-Indo-European *pap-(“ pock mark, nipple”)). Akin to Old English pipliġende(“having shingles”).

etymonline

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pimple (n.)

"small, often inflamed, swelling of the skin," late 14c. (early 14c. as a surname), of unknown origin; perhaps related to Old English pipligende "having shingles;" also compare Latin papula, papilla (see pap (n.2)). As a verb, "to cover with pimples," from c. 1600. Related: Pimples.