sarcomere
Concise Oxford English Dictionary © 2008 Oxford University Press:
sarcomere /ˈsɑːkə(ʊ)mɪə/
▶noun Anatomy a structural unit of a myofibril in striated muscle.
– origin C19: from Gk sarx, sark- ‘flesh’ + meros ‘part’.
'sarcomere' also found in these Oxford entries:

