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? from French choisir, in same sense;
or perhaps rather an assimilation of choose v. (? in form chose) to the n. chois, choice, so that choice, choise would form a pair like advice,advise, use, use, glass, glaze.
If it had been only Scottish, the oi might have originated as the 16th c. Scottish spelling of ō.
From: A Book of Scotish Pasquils, 1568-1715
Edited by James Maidment, 1868
Pasquil on the Stair Family