1. thin layer of tissue: a thin flexible sheet of tissue connecting, covering, lining, or separating various parts or organs in animal and plant bodies, or forming the external wall of a cell
2. thin porous sheet: a thin, pliable, and often porous sheet of any natural or artificial material
3. piece of parchment: a piece of parchment forming part of a roll
[15th century. Directly or via French< Latin membrana "skin" < membrum "limb, part"]
