1550s, "tribe of Asiatic nomads living in tents," from West Turkic (compare Tatar urda "horde," Turkish ordu "camp, army"), borrowed into English via Polish, French, or Spanish. OED says the initial -h- seems to have been acquired in Polish. Transferred sense of "any uncivilized gang" is from 1610s. Related: Hordes.
updated on August 19, 2015