Epithelium
/ˌɛpɪˈθiːliəm/noun
A layer of cells covering the body’s external surfaces and lining internal cavities and organs.
Did you know?The term was coined in early modern anatomy after Greek epithelium was used for tissue covering the nipple, before its meaning expanded to other protective cell layers.
Etymological Timeline
Ancient Greek
Greek
epi-
“upon, on, over”
Ancient Greek
Greek
thēlē
“nipple or teat”
Ancient Greek
Greek
epithēlē
“something placed upon the nipple”
1703
Modern Latin
epithelium
“A covering tissue, originally referring to tissue over the nipple”
19th Century
Medical English
epithelium
“A layer of cells covering or lining a body surface”
Modern English
English
epithelium
“The cellular tissue lining external and internal surfaces of the body”