/ret'n ak"yeuh leuhm/ , n. , pl. retinacula /-leuh/ .
1. Anat. , Zool. any of various small structures that hook, clasp, or bind other structures to move them or hold them in place.
2. Entomol. a bristle on the butterfly forewing that clasps to the frenulum of the hindwing.
[ 1815-25; retinaculum tether, rope which holds fast or restrains, equiv. to retin ( ere ) to hold fast, RETAIN + -a- (from v. stems ending in -a-; cf. GUBERNACULUM) + -culum -CULE 2 ]