from the GNU version of the Collaborative International Dictionary of English
- n. A mathematical object, or a physical representation of it, which is a two-dimensional sheet with only one surface. It is constructed or visualized as a rectangle, one end of which is held fixed while the opposite end is twisted through a 180 degree angle and joined to the fixed end. It is a two-dimensional object that can only exist in a three-dimensional space.
Sorry, no etymologies found.