- Douglas Frame, The Myth of Return in Early Greek Epic, 1: Formal Evidence for the Etymology of Greek nóos, https://chs.harvard.edu/publications.sec/online_print_books.ssp/. Center for Hellenic Studies, Washington, DC. September, 2005
1. Formal Evidence for the Etymology of Greek nóos
Various attempts have been made to etymologize Greek nóos, but none of these has carried wide conviction. The word permits a large number of formal reconstructions, and this helps to explain both the number of attempted etymologies and the uncertainty of all of them.
The crucial problem is the hiatus, which may be accounted for by the loss of original –w-, –j-, or –s-, or may even be regarded as original itself. Complicating this situation is the ambiguity of the initial n, which may be either original or descended from an original sn– (as in nípha, “snow,” from *snig?h–?). Multiplying the two uncertainties by each other produces a total of eight possible reconstructions. 
This field may be reduced sharply, however. The decipherment of the Linear-B tablets has produced a new and important piece of evidence regarding the hiatus. The evidence does not show which of the four possibilities is correct, but it does remove from consideration the one that has most often been assumed by etymologists.
In the tablet KN V 962 is found the form wi-pi-no-o; this has been interpreted as the personal name Wiphínoos, classical Greek Iphínoos, a compound form with the word nóos as its second element. The spelling no-o of this element is decisive against the reconstruction *(s)now-os for –w– is preserved in Mycenean (as in the first element Wiphi-), and the spelling would have been *wi-pi-no-wo.  This factor immediately disposes of three attempted etymologies. Two of these, connecting nóos with neú?, “nod,” and né?, “swim,” were in any case unlikely.  But the third, proposing a connection with Gothic snutrs, “wise, intelligent,” was defended by Eduard Schwyzer and is given preference by Hjalmar Frisk.  This too must now be abandoned.
Given the impossibility of connections with Gothic snutrs and Greek né?, there is no reason to postulate an original sn– initial. This was, in any case, unlikely on purely formal grounds, since there is no trace of a double consonant initial either in Homeric compounds or in the scansion of Homeric verse. As against the –nn– in, for example, agánniphos, “very snowy,” there is only –n– in ankhínoos, ano?m?n, anó?tos, ánoos, Alkínoos, Antínoos, Arsínoos, Astúnoos, Autónoos, Hippónoos, Iphínoos, Pontónoos, and Prónoos. Likewise, there is nothing corresponding to the scansion of óre? niphóenta, “snowy mountains,” (xix 338) in sequences that involve nóos.  Admittedly, the treatment in these matters does not always correspond to etymological realities; but the onesidedness of the evidence cannot be ignored where there is no strong external reason for doubt.
These considerations reduce the possibilities to three: *no-os, *noj-os, and *nos-os. The first of these is in fact very unlikely, for nóos, as Frisk points out, is doubtless an old, inherited verbal noun (“zweifellos ein altererbtes Verbalnomen”), and as such should be connected with a verbal root – namely, with a root having the shape CeC- (where C = consonant).
The second form, *noj-os, satisfies this condition; it also conforms to the Mycenean evidence, since the loss of intervocalic yod is attributable to Common Greek. Furthermore, a root *nej– is attested with an appropriate meaning in Sanskrit. Related to the verb nayati, “lead,” is the thematic noun naya-?, which has the meanings “leading, performance, behavior, worldly wisdom, policy, fundamental principle, system, theory.” According to McKenzie, who proposed this connection with Greek nóos, “it is not easy to see how far the resemblance of meaning between nóos and naya-? is due to the survival of inherited senses in both cases, and how far to independent but parallel development of fresh meanings in each language. That the passage from ‘lead’ to ‘think’ was possible we know from Latin duco and Greek h?géomai. It may have occurred independently in Greek and in Sanskrit.” 
McKenzie’s etymology is possible, but it has serious problems. Naya-? does not appear until the post-Vedic period, and may well be an independent formation in Sanskrit. The appropriate meanings, moreover, seem clearly derivative, and in any case are not very close to the meaning of Greek nóos. One might still suppose an independent semantic development in Greek, except for the most serious difficulty of all: one would be speculating about a verbal root which is otherwise unattested in Greek. As far as we know, there was no Greek root nej-.
The form that remains is *nos–os. This, too, conforms to the Mycenean evidence, since the loss of intervocalic s is also attributable to Common Greek. In Mycenean this s probably survived as h in pronunciation, but the feature is usually not represented in the writing system (cf. the s-stem dative we-te-i, later Greek (w)étei, from *wetesi). Furthermore, there is a well-attested verbal root nes– in Greek: namely the root of néomai, “return home,” in which etymological s is guaranteed by the nominal form nóstos.
The formal evidence thus indicates that nóos and néomai have the same relation to each other as lógos and lég?, phóros and phéro, phóbos and phébomai. This situation has already been recognized, as is indicated by Hugo Mühlestein’s remark that, in the opinion of Ernst Risch and Alfred Heubeck, “no?s could, in spite of the semantic difficulty, belong to the same root as néomai” (“no?s könnte, trotz der semantischen Schwierigkeit, zur gleichen Wurzel gehören wie néomai”). 
Mühlestein himself connects the element –noos in names like Iphínoos with the verb néomai in a transitive sense, “bring home,” and he would like to distinguish these from other compound names which clearly have to do with nóos, “mind.”  His translation “he who brings safely home by means of his strength” (“der mit Kräften heim rettet”) for Mycenean Wiphínoos in fact puts the present argument in danger of circularity, since it was merely assumed that this proper name has to do with nóos, “mind.” The circularity can be overcome only by showing that in reality there is only one class of compounds in –noos, insofar as the root is concerned. This, in turn, can be shown only when the “semantic difficulty” of connecting nóos and néomai is removed. Such, in any case, is the main problem to be solved in establishing the proposed etymology of nóos. The danger of circularity in the formal argument gives appropriate emphasis to the need for convincing semantic arguments. On the success of the latter the whole case must rest.
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