An archaic or obsolete term for one who counts or a person who performs counting duties; a counter or accountant.
From count + -or (agent noun suffix). An older English term that fell out of use as 'counter,' 'accountant,' and 'clerk' became standard terminology.
This is one of those wonderful old job titles that shows how English constantly creates new words for occupations—today's 'data analyst' is basically the modern version of what a medieval 'countor' would do.
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