[ 'fri:njʊləm ]
■ noun
1》 Anatomy a small fold or ridge of tissue, in particular a fold of skin beneath the tongue or between the lip and the gum.
2》 Entomology a bristle or row of bristles on an insect's hindwing which keeps it in contact with the forewing.
Origin
C18: mod. L., dimin. of L. frenum 'bridle'.