I would love a definitive answer on whether a heptagon has an alternative name, the septagon. so I have been told!
no it doesn't, to place it bluntly
The septagon is an invention of the primary school teacher designed to make it easier on small children, as "Septum" is the Latin for 7.
Does it really matter? Hepta or septa, anyone hearing it would know you meant 'seven-sided polygon'.
What if all the other shapes got new names too? We'd never know which name to call them by! The seven sided shape should stick with its name of Heptagon!
I have just found out that Heptagon come from the Greek word for 7, and hexagon and icosahedron, while all the others are Latin. I say standardise, therefore I am pro sexagon, septagon and Didecahedron.