Where does “icosihenagon” come from?

icosihenagon (English) comes from Ancient Greek εἰκοσιέν, from Ancient Greek ἕν, from Ancient Greek εἷς, from Proto-Hellenic hens, from Proto-Indo-European sḗm, from Proto-Indo-European sem- — together, one.

icosihenagon (English): A polygon with twenty-one edges and twenty-one...

Definitions

A polygon with twenty-one edges and twenty-one...

Ancestry of “icosihenagon”, step by step

Step	Language	Word	Meaning
1	Ancient Greek	εἰκοσιέν	twenty-one
2	Ancient Greek	ἕν	neuter nominative/accusative/vocative singular of...
3	Ancient Greek	εἷς	one
4	Proto-Hellenic	hens	cardinal number 1 Previous: n/a Next: *dúwō;...
5	Proto-Indo-European	sḗm	one
6	Proto-Indo-European	sem-	together, one

Every word from Proto-Indo-European sem- →Every word from Proto-Indo-European sḗm →Every word from Proto-Hellenic hens →