What are the 20 polygons?

Hendecagon has 11 sides,dodecagon has 12 sides,triskaidecagon has 13 sides,tetradecagon has 14 sides,pentadecagon has 15 sides,hexadecagon has 16 sides,17 sides is heptadecagon,octadecagon have 18 sides,enneadecagon has 19 sides,20 sides is called as icosagon. The prefix of that 9 polygons is Greek. A polygone with 4 sides is called a quadrilateral.