shire n.

mid-14c., "a shire, a definite division of a country or state for political and administrative purposes," from Anglo-French counte, from Late Latin comitatus "jurisdiction of a count," from Latin comes (see count (n.1)). It replaced Old English scir "shire."

From late 14c. as "the domain of a count or earl." County palatine, one distinguished by special privileges (Lancaster, Chester, Durham) is from mid-15c. County seat "seat of the government of a county" is by 1848, American English.

1086, Cestre Scire, from Chester + scir "district" (see shire). Cheshire cat and its proverbial grin are attested from 1770, but the signification is obscure.

I made a pun the other day, and palmed it upon Holcroft, who grinned like a Cheshire cat. (Why do cats grin in Cheshire?—Because it was once a county palatine, and the cats cannot help laughing whenever they think of it, though I see no great joke in it.) I said that Holcroft, on being asked who were the best dramatic writers of the day, replied, "HOOK AND I." Mr Hook is author of several pieces, Tekeli, &c. You know what hooks and eyes are, don't you? They are what little boys do up their breeches with. [Charles Lamb, letter to Thomas Manning, Feb. 26, 1808]