from The American Heritage® Dictionary of the English Language, 4th Edition
- n. Membranous tissue composed of one or more layers of cells separated by very little intercellular substance and forming the covering of most internal and external surfaces of the body and its organs.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. A membranous tissue composed of one or more layers of cells which forms the covering of most internal and external surfaces of the body and its organs: internally including the lining of vessels and other small cavities, and externally being the skin.
from the GNU version of the Collaborative International Dictionary of English
- n. The superficial layer of cells lining the alimentary canal and all its appendages, all glands and their ducts, blood vessels and lymphatics, serous cavities, etc. It often includes the epidermis (i. e., keratin-producing epithelial cells), and it is sometimes restricted to the alimentary canal, the glands and their appendages, -- the term endothelium being applied to the lining membrane of the blood vessels, lymphatics, and serous cavities.
from The Century Dictionary and Cyclopedia
- n. In anatomy, the superficial layer of cells of mucous membranes, covering the connective-tissue layer, corresponding to the epidermis of the outer skin and continuous with it at the mouth and other natural openings.
- n. In ornithology, specifically, the dense, tough cuticular lining of the gizzard. It is sometimes even bony, and sometimes deciduous.
- n. In botany, a delicate layer of cells lining the internal cavities of certain organs, as the young ovary, etc.: also applied to the thin epidermis of petals.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. membranous tissue covering internal organs and other internal surfaces of the body
New Latin epithēlium : epi- + Greek thēlē, nipple; see dhē(i)- in Indo-European roots.(American Heritage® Dictionary of the English Language, Fourth Edition)
Modern Latin epithēlium, from Ancient Greek ἐπί (epi, "on, atop, epi-") + θηλή (thēlē, "nipple"). (Wiktionary)