A line segment in a polygon connecting any two nonconsecutive vertices is called a diagonal.
If I understand what you mean, then another way to say is "No two of its vertices can form a line segment that falls outside of the polygon". In that case, it is called a convex polygon.
It's called a side or edge.
The points where the line segments that form a polygon meet (i.e., the corners) are called the vertices of the polygon. The singular form is vertex.
A segment.
Line
A line segment joining two adjacent vertices of a polygon is called an edge or a side. A line segment joining two non-adjacent vertices is called a diagonal.
It is called a side or edge.
side
A line segment connecting two vertices of a polygon is called an edge if the vertices are adjacent to one another. Otherwise it is called a diagonal.
The line segments that form a polygon called are called sides or edges.
A segment connecting any two non-adjacent vertices in a polygon is called
A line segment in a polygon connecting any two nonconsecutive vertices is called a diagonal.
………………………… is a line segment that joins two vertexof a polygon but is not a side of the polygon.
Diagonal
If I understand what you mean, then another way to say is "No two of its vertices can form a line segment that falls outside of the polygon". In that case, it is called a convex polygon.
It's called a side or edge.