Anatomy,Zoology. any of various small structures that hook, clasp, or bind other structures to move them or hold them in place.
2.
Entomology. a bristle on the butterfly forewing that clasps to the frenulum of the hindwing.
Origin: 1815–25; < NL; L retināculum tether, rope which holds fast or restrains, equiv. to retin(ēre) to hold fast, retain+ -ā- (from v. stems ending in -ā-;cf. gubernaculum) + -culum-cule2