The position, office, or period of service of a counsellor (a person who gives advice or legal counsel).
From counsellor (British spelling of counselor) plus the -ship suffix meaning office or rank. Counsellor comes from Old French conseil meaning 'advice,' ultimately from Latin consilium.
The -ship ending is used for all kinds of leadership roles—friendship, leadership, championship—but counsellorship is the fancy formal version you'd use in legal documents or government positions!
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