Notes: The root is attested only in Nakh, but cf. Urart. nek- 'to flow, flow out' (see Diakonoff-Starostin 1986, 31).
The Urartian parallel makes a loan from Iranian improbable: thus Osset. nakä 'swimming' is probably a loan from Nakh, not vice versa (pace Abayev 1973, 152) and hardly goes back to *snāka-.