membrane

Etymology

Late Middle English, borrowed from Latin membrāna (“skin or membrane that covers parts of the body”), from membrum (“a limb or member of the body”) + -āna. Doublet of membrana.

noun

1. (anatomy, zootomy) A flexible enclosing or separating tissue forming a plane or film and separating two environments.
   1. A mechanical, thin, flat flexible part that can deform or vibrate when excited by an external force.
   2. A flexible or semiflexible covering or waterproofing whose primary function is to exclude water.
   3. (biology) A microscopic double layer of lipids and proteins forming the boundary of cells or organelles.
2. A piece of parchment forming part of a roll.