The term complex polygon can mean two different things:
In geometry, a complex polygon is a polygon in the complex Hilbert plane, which has two complex dimensions.
A complex number may be represented in the form , where and are real numbers, and is the square root of . Multiples of such as are called imaginary numbers. A complex number lies in a complex plane having one real and one imaginary dimension, which may be represented as an Argand diagram. So a single complex dimension comprises two spatial dimensions, but of different kinds - one real and the other imaginary.