The term is of vast antiquity and presents a remarkably regular form:
Hittite iúkan, Vedic Sanskrit युग (yugá, meaning yoke, but also: pair; yoga comes from the same root), Ancient Greek ζυγόν (zugόn), Latin iugum, Gothic juk (German Joch), Old Church Slavonic igo, Lithuanian jungas, etc. So enduring was this root that it remains productive to our days in the sense of (re)uniting something, as under a “yoke”, into a “junc-tion”… that when the modern Lithuanian language had to invent the notion of a political “Union”, as in the European Union, it used the old jug-/jung– : Europos Są-junga…
Gamkrelidze and Ivanov, in their groundbreaking The Indo-European language and the Indo-Europeans (Индоевропейский язык и индоевропейцы, Tbilisi, 1984) have convincingly reorganised the traditionally accepted phonetic system of the Proto-Indo-European by giving the voiced consonants (b, g, d) the value of the Caucasian ejectives, which are unvoiced gutturals (p‘, t‘, q‘, this last sounding like the Semitic q). From this perspective, the famous law of the German ”Lautvershiebung“, whereby the Indo-European voiced sounds become un-voiced in German (cf. Latin iug-um – Gothic juk) loses its relevance: it is Germanic (and Armenian) which prove to be more archaic, closer to the pan-Caucasian sound system, while the other branches of the I-E family have innovated by voicing the q‘ into g. The root would thus be: *juq‘ -, and not *jug-, as accepted historically.
From Indo-European, the term has passed, in its voiced form, as an archaic loan into the South-Caucasian (Kartvelian) languages: Georgian uγel, Mingrelian uγu, Svan uγwa.
The Indo-european etymologies proposed traditionally are unconvincing and circular, like: ”from verb *yeug– (join, unite)“. It is here that a comparison, never effectuated, with the North-East Caucasian languages, totally unrelated to the South Caucasian Kartvelian languages, brings a possible solution.
Chechen, and all the languages from Daghestan, present a rare particularity: they are ”class languages“. All words are distributed between various nominal classes corresponding to our grammatical genders. Where Indo-European languages have historically three grammatical genders, Chechen has six. These are indicated by a set of four markers appended initially to words: v- indicates masculinity, like in: vasha = brother; y- indicates a female person, like in
yisha = sister, but it can also be the mark of some neuters, alternating with b- and d- to produce various notions. The set of v-, y-, b-, d- initial markers are also appended to verbs and adjectives, which change their beginning according to the gender of the ruling noun.
This creates a heavy but predictable grammatical machinery, and also an easily analysable lexical corpus. Thus, from the root –q‘-, ”to divide“ / ”to reunite”, Chechen possesses the set vuq‘, yuq‘, buq‘, duq‘ : thus, duq‘ and vuq‘ commonly indicate the yoke; yuq‘ is the ”middle“, or a ”pair“… buq‘ is the spine, the backbone, or a mountain ridge…
The Chechen series is extremely productive, yuq‘ being the most used, and, besides various verbs with meanings going from ”reunite“ to ”put together“ and ”put in the middle“ (cf. Latin derivatives, from jugum > con-jugare, sub-jugare, etc., or Sanskrit yoga, from the same root), yuq‘ can also take on temporal values: Chechen yuq‘-yuq‘a = from time to time, periodically (cf. Sanskrit yugá, ”period of time“, in parallel with ”yoke“); and, very important from a socio-cultural point of view, to get married, to ”go under the same yoke“: hence the Latin con-iux, spouse, (under the same con-jug-al yoke), the notion being borrowed as well into Old Georgian: me-uγle = spouse.
The morphological and semantical concordances between Chechen yuq‘ (and the other Daghestani languages) on the one hand, Indo-European *yuq‘ on the other are too systematical, coherent and symmetrical to be due to mere chance. The disturbing fact is that the root *yuq‘- is unexplained in Indo-European, while in Chechen-Daghestani it is native, part of the system of indicators of nominal classes y-, v-, b-, d-…
The word seems thus to have been borrowed by the Indo-Europeans from the North-Caucasians… together with the tool it designated : the ”yoke“ itself.
See also : अ अ : Eugène Ionesco as a Yogi: ”La philologie mène au crime…”