A four-sided plane figure with reverse edges parallel.

A convex quadrilateral which each set of opposite edges are parallel as well as equal length.

A right-lined quadrilateral figure, whose reverse edges tend to be parallel, and consequently equal; -- often restricted in popular usage to a rectangle, or quadrilateral figure that is longer than it is broad, with correct perspectives.

In geometry, a quadrilateral whoever other sides tend to be parallel.

A pantograph.

a quadrilateral whose other sides tend to be both synchronous and equal long

## How would you define parallelogram?