Definition of "membrane"

(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.  examples

2. A flexible or semiflexible covering or waterproofing whose primary function is to exclude water.  examples

3. (biology) A microscopic double layer of lipids and proteins forming the boundary of cells or organelles.

A piece of parchment forming part of a roll.  examples