mitochondrion

Concise Oxford English Dictionary © 2008 Oxford University Press:
mitochondrion /ˌmʌɪtə(ʊ)ˈkɒndrɪən/

▶noun (pl. mitochondria /-rɪə/) Biology a structure found in large numbers in most cells, in which respiration and energy production occur.

– derivatives
mitochondrial adjective.

– origin early 20th cent.: mod. L., from Gk mitos ‘thread’ + khondrion (dimin. of khondros ‘granule’).