Middle English word mencioun comes from Latin mens (Intellect. Mind. Reasoning, judgement.)

Detailed word origin of mencioun

Dictionary entry	Language	Definition
mens	Latin (lat)	Intellect. Mind. Reasoning, judgement.
mentio	Latin (lat)	Mention, a calling to mind.
mention	Old French (fro)	Mention (act of mentioning).
mencioun	Middle English (enm)	Mention (act of mentionining).