Where does “Pentagon” come from?

Pentagon (Romanian) comes from English Pentagon, from Middle French pentagone, from Late Latin pentagonum, from Ancient Greek πεντάγωνον, from Ancient Greek πεντάγωνος, from Ancient Greek γωνία, from Ancient Greek γόνυ, from Proto-Hellenic gónu — knee.

Pentagon (Romanian): Pentagon

Definitions

Pentagon

Ancestry of “Pentagon”, step by step

Pentagon traces back through two separate lines of ancestry.

via English Pentagon

Step	Language	Word	Meaning
1	English	Pentagon	The headquarters of the United States Department of Defense
2	Middle French	pentagone	—
3	Late Latin	pentagonum	pentaphyllon
4	Ancient Greek	πεντάγωνον	pentagon
5	Ancient Greek	πεντάγωνος	five-angled
6	Ancient Greek	γωνία	corner, angle; joiner's square; cornerstone
7	Ancient Greek	γόνυ	knee
8	Proto-Hellenic	gónu	knee
9	Proto-Indo-European	ǵónu	knee

via French pentagone

Step	Language	Word	Meaning
1	French	pentagone	pentagon
2	Latin	pentagonus	—

Words derived from “Pentagon”

pentagonal

Every word from Proto-Indo-European ǵónu →Every word from Proto-Hellenic gónu →Every word from Ancient Greek γόνυ →