Intramural sports or intramurals are recreational sports organized within a particular institution, usually an educational institution, or a set geographic area. The term, which is chiefly North American, derives from the Latin words intramuros meaning "within walls", and was used to describe sports matches and contests that took place among teams from "within the walls" of an institution or area. The term dates to the 1840s. It is contrasted with extramural, varsity or intercollegiate sports, which are played between teams from different educational institutions. The word intermural, which also correctly means "between institutions", is a common error for "intramural".

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Source:  Wikipedia