Thylakoids
/ˈθaɪ.lə.kɔɪdz/noun
Membrane-bound sacs inside chloroplasts where the light-dependent reactions of photosynthesis occur.
Did you know?The term was coined in modern scientific Greek from a root meaning “pouch” or “sac,” showing how scientists often built new words from ancient language to name hidden structures inside cells.
Etymological Timeline
Ancient Greek
Greek
θύλακος (thýlakos)
“pouch, bag, sack”
19th Century
Greek
θυλακοειδής (thylakoeidḗs)
“pouch-like, sac-shaped”
1900s
Scientific Latin/English
thylakoid
“a saclike structure, especially the flattened membrane sacs in chloroplasts”
Modern English
English
thylakoid
“a flattened membrane sac in chloroplasts or cyanobacteria”