sarcomerePronunciation: /ˈsɑːkə(ʊ)mɪə/Definition of sarcomere noun Anatomy a structural unit of a myofibril in striated muscle, consisting of a dark band and the nearer half of each adjacent pale band. Origin: late 19th century: from Greek sarx, sark- 'flesh' + meros 'part'sarcomere in other Oxford dictionaries Definition of sarcomere in the US English dictionary