Simply that: "irregular octagon".
An octagon. Or more specifically, an irregular octagon.
An irregular octagon.
I would call it an irregular octagon, or an irregular 8-sided polygon.
It is called an octagon and an irregular octagon can take any shape.
An irregular octagon
It is called an irregular octagon.
An octagon can be an irregular shape, but a regular octagon has all sides and angles equal.
An octagon that is not irregular is a regular octagon, one in which each of the eight sides os the same length
It is a shape that has 8 sides but does not look like a regular octagon. As long as it has 8 sides it is an irregular octagon.
It can be regular or irregular although irregular is more probable.
A regular octagon will not tessellate but an irregular one can.
A regular octagon will not tessellate but an irregular one can.