Forum

google

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late Middle English (in forum (sense 3)): from Latin, literally ‘what is out of doors’, originally denoting an enclosure surrounding a house; related to fores ‘(outside) door’. forum (sense 1) dates from the mid 18th century.

wiktionary

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From Latin forum(“public market place, forum”). Doublet of fuero.

etymonline

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forum (n.)

mid-15c., "place of assembly in ancient Rome," from Latin forum "marketplace, open space, public place," apparently akin to foris, foras "out of doors, outside," from PIE root *dhwer- "door, doorway." Sense of "assembly, place for public discussion" first recorded 1680s.