Basic equivalent of the poetic term labbu, may be related to Hbr. nāḥāš, Ugr. nḥš ‘snake’ (HALOT 690, DUL 628; for the semantic shift see SED II No. 159).
Cf. also nēšu ša ḳaḳḳari ‘snake’, literally ‘lion of the earth’ (Kogan 2011:211).
may go back to the verbal root *nḥš‘to live, to be alive’ preserved in Akk.nêšu. For semantic development see Buck 1949:137 (numerous IE precedents) and, in the Semitic domain, Hbr. ḥayyā‘animaľ