well if you take octagon (8 sides) , in 3d shapes octagon is probably called octagonal prism. and the sides are actually called faces. AND a 7 sided shape , a heptagon, is called heptagonal prism

I assume you want the name of each shape, not just the generic polygon which refers to any multi-sided shape. 5 sides - pentagon 6 sides - hexagon 7 sides - heptagon 8 sides - octagon 9 sides - nonagon 10 sides - decagon

6 sides is a hexagon a shape with 7 sides is a heptagon don't get them mixed up and besides that question was already on wikianswers and it was answered