A stop sign is octagonal in shape.
An octagonal prism
So that if the sign is unreadable due to snow/dirt, it can still be recognised by the shape alone.
It's an octagon. Look at a stop sign- they're octagonal.
It is an octagonal prism
An octagonal shape has 8 sides
The octagonal shaped sign was colorful.
Octagonal prism
A beehive
British stop signs are octagonal to make them easily identifiable even when they are obscured by dirt or snow.
16. There is an octagonal shape, with eight vertices, at each end.
It is octagonal the same us in the USA. However, there are very, very few of them because of all the round-a-bouts.
An octagonal prism.