polygon (n.) Look up polygon at Dictionary.com
1570s, from Latin polygonum, from Greek polygonon, noun use of neuter of adjective polygonos "many-angled," from polys "many" (from PIE root *pele- (1) "to fill") + -gonos "angled," from gonia "angle" (from PIE root *genu- (1) "knee; angle"). Related: Polygonal.