-gon

1.
a combining form meaning “angled,” “angular,” used in the formation of compound words:
polygon; pentagon.
Compare gonio-.
Origin
< Greek -gōnos, derivative of gōnía angle, akin to góny knee
British Dictionary definitions for -gon

-gon

combining form
1.
indicating a figure having a specified number of angles: pentagon
Word Origin
from Greek -gōnon, from gōnia angle