13th cent. Old Spanish yugo, iuuo. Borrowed from Latin iugum 'id.'
From Proto-Italic *jugo- 'id.' From Proto-Indo-European *i̯ug-o- "yoke," but more literally "joined together." From the root *i̯eu̯g- "to yoke together."
Romance: Western Vulgar Latin: Asturian xugu, Portuguese jugo, Galician xugo, Catalan jou, French joug, Italian giogo ; Eastern Vulgar Latin: Aromanian chubo, Romanian jug ; Sardinian: giú
Indo-European: Celtic: Old Irish cuing "yoke," Middle Welsh iou 'id.,' Middle Breton yeu 'id.,' Cornish ieu 'id.;' Germanic: Gothic juk "yoke," Old Norse ok 'id.,' Old High German joh 'id.,' Old Saxon juk 'id.,' Old English geoc 'id.' (English yoke); Balto-Slavic: Old Church Slavonic igo "yoke," Russian ígo 'id.,' Czech jho 'id.,' Polish jugo 'id.,' Slovene igọ̑ 'id.,' Lithuanian jùngas 'id.,' Latvian jûgs 'id.;' Indo-Iranian: Sanskrit yúj- "ally," Young Avestan yuiiō- "yoke;" Anatolian: Hittite iūk- "yoke," Cuneiform Luwian Lycian 'id.'Myriad written attestation in Spanish and in Romance languages affirm that this is not a learned borrowing from Latin, yet Corominas (1991) notes that we should expect **jogo from iugum, and not yugo. Preservation of yu- could be from Leonese influence.Old Spanish iuuo (early 13th cent.), however surprising, cannot be dismissed as a writing error: in the Almerían dialect we find a modern reflex in huvo. This must be a continuation of Vulgar Latin *iuum. The ability to reconstruct a word for yoke in Proto-Indo-European proves that the ancient Indo-Europeans had draft animals used to pull wheeled carts.