Hampshire

wiktionary

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English ham + shire (county), from Old English Hamtunscīr. The 'p' evolved phonetically between [m] and [sh], as with Thom'p'son.

etymonline

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Hampshire

reduced from Old English Hamtunscir; named for the city of Southampton, which originally was simply Hamtun. Norman scribes mangled the county name to Hauntunescire, later Hantescire, hence the abbrev. Hants.