sarcoplasmPronunciation: /ˈsɑːkə(ʊ)plaz(ə)m/Definition of sarcoplasm noun [mass noun] Physiology the cytoplasm of striated muscle cells. Derivatives sarcoplasmic adjective Origin: late 19th century: from Greek sarx, sark- 'flesh' + plasmasarcoplasm in other Oxford dictionaries Definition of sarcoplasm in the US English dictionary