A vertex and its plural is vertices
it is called a ...
The corner of a polygon is technically known as a vertex.
A vertex
It is a vertex which is a corner of a polygon
diagonal
angle
Cone
It is a 'corner' of a polygon.
On a protractor and at each corner (vertex) of the polygon.
The geometrical word for the corner of a polygon is its vertex of which the plural is vertices.
It is called a vertex (plural-vertices).
Vertex, I believe.