A trapezoid only has only two parallel sides.
A triangle. It has only three sides!
An impossible figure
Parallelogram
A polygon is a 2-dimensional closed figure that has at least three sides. A pentagon is a 2-dimensional closed figure that has five and only five sides, so it is a kind of polygon.
A trapezoid is a four sided figure with at least one set of parallel sides
A 2-dimensional figure can have any number of sides more than 2.
OctagonAn octagon is a 2-D figure with 8 sides.
A hexagon is a 2-dimensional figure with six sides. In general, a 2-dimensional figure with many sides is called a polygon.
Oblong
inscribed angles
A tangent perhaps?