From Proto-Germanic*harbistaz, from Proto-Indo-European*kerp-. Cognate with Old Frisian herfst (modern West Frisian hjerst), Old Saxon hervist (modern Low German harvst), Dutch herfst, Old High German herbist (German Herbst). The Indo-European root is also the source of Ancient Greek καρπός(karpós, “fruit”), Latin carpō(“pick, pluck”), Middle Irish corrán(“sickle”), Lithuanian kirpti(“cut”), Old Church Slavonic чрьпати(črĭpati) (Russian серп(serp, “sickle”)).
A North Germanic variant Proto-Germanic *harƀustaz was the source of Old Norse haust (Danish høst, Icelandic haust and Swedish höst).