Main Entry: myo·fi·bril

Pronunciation: \ˌmī-ə-ˈfī-brəl, -ˈfi-\

Function: noun

Etymology: New Latin myofibrilla, from my- + fibrilla fibril

Date: 1898

: any of the longitudinal parallel contractile elements of a muscle cell that are composed of myosin and actin

— myo·fi·bril·lar \-brə-lər\ adjective