English word chloro- comes from Proto-Indo-European *ǵʰloū-

Detailed word origin of chloro-

Dictionary entry	Language	Definition
*ǵʰloū-	Proto-Indo-European (ine-pro)
*ghlo-	Proto-Indo-European (ine-pro)
χλωρός	Ancient Greek (grc)
chloro-	English (eng)	(chemistry) Containing chlorine.. Green in color.