An irregular* pentagon *means that the sides are not all the same length
Square
triangle
a triangle.
A square based pyramid.
An irregular* pentagon *means that the sides are not all the same length
Combining form for shape
hexagon
Square
a pentagon
triangle
circle triangle square
a triangle.
at the bottom is is a square and triangle on the sides
A square based pyramid.
Square.
There is no specific name because there is no specific shape. The shape could have anything from 5 to 13 sides depending on the sizes and orientations of the triangle and square.