/ ˈfrenjələm; NAmE ; BrE also ˈfriːn-/ ( BrE also frae·nu·lum ) /ˈfriːn-/ noun
( anatomy ) a small fold of skin that prevents an organ from moving too much, for example the fold of skin under the tongue
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WORD ORIGIN
early 18th cent.: modern Latin , diminutive of Latin frenum bridle.