/ˈmemˌbrān/
Noun, pl. membranes
1. A mechanical, thin, flat flexible part that can deform or vibrate when excited by an external force. (wiktionary.org)
2. A flexible or semi-flexible covering or waterproofing whose primary function is to exclude water. (wiktionary.org)
3. A thin layer of tissue that covers a surface, lines a cavity, or divides a space or organ. (medical-dictionary.thefreedictionary.com)
(Biology)
1. A thin layer of tissue covering a surface or lining a cavity, space or organ. (biology-online.org)
2. A flexible enclosing or separating tissue forming a plane or film and separating two environments (usually in a plant or animal). (wiktionary.org)
3. A cell membrane. (biology-online.org)
(Chemistry)
1. A thin pliable sheet of material that is permeable to substances in solution. (wiktionary.org)
Word origin: A term in anatomy, from Latin membrana “a skin, membrane; parchment (skin prepared for writing),” from membrum “limb, member of the body.”