CAD online vol.11/21 1980 N pt.2 sub voce “nāru A” p.368:

nār = nāru A s. fem.; 1. river, canal . . . from OAkk. on; wr. syll. and ÍD (in OB, Mari also ÍD.DA); cf. alap nāri, atān nāri, erib nāri, nāriš, nārtu.

Akkadian Dictionary online © Association Assyrophile de France n.d.:

1.  nāru [ÍD] (n. fem.; pl. nārātu) = river, watercourse, canal; comparison with other Semitic languages:

a.  Proto-Semitic: *nahar
b.  Arabic: nahr نَهْر
c.  Syriac: nahrā ܢܲܗܪܵܐ
d.  Hebrew: nāhār נָהָר
e.  Ugaritic: nhr

2.  nārum = river; comparison with other Semitic languages:

Syriac: nahrā ܢܲܗܪܵܐ

Edwin Norris Assyrian Dictionary online 1872 vol.3 sub voce NHR p.997:

nār = nahru; a River.  Heb. נָהָר.

Norris op. cit. online sub voce MRR p.862:

nahr marratu, nahr marrati, nahr marratā = “the Sea, Sea’s” infl. here in fem. sing. nominative, genitive & accusative case respectively.

n.b. ancient Hellenic formula ποταμὸς Ὠκεανός “river Oceanus” styled after this documentary Near Eastern resource nār marratu(m) “(river) sea” quod supra vide and seen here in just a few mythological illustrations to follow:

1.  Homer through gratuitous assent of the manageably copious Perseus Digital Library Project online since joyful 1995 Tufts University, Medford/Somerville near Boston, Massachusetts USA (CC) 2006 Homeri Opera vol.1-5 Oxford, England UK, Oxford University Press © 1920 Iliad 3rdEd by DB Monro and TW Allen Σ (18) 607-608 c. 750 BC:

     ἐν δ᾽ ἐτίθει ποταμοῖο μέγα σθένος Ὠκεανοῖο
     ἄντυγα πὰρ πυμάτην σάκεος πύκα ποιητοῖο.

     And there he [i.e. Hephaestus] the great strength of river Oceanus put
     Along outermost rim of shield with a thick body made.

2.  Homer op. cit. Ψ (20) 7:

     οὔτέ τις οὖν ποταμῶν ἀπέην νόσφ᾽ Ὠκεανοῖο,

     Nor indeed was any of the rivers apart from Oceanus away;

3.  Homer op. cit. Ξ (14) 244sqq.:

     ἄλλον μέν κεν ἔγωγε θεῶν αἰειγενετάων
     ῥεῖα κατευνήσαιμι, καὶ ἂν ποταμοῖο ῥέεθρα
     Ὠκεανοῦ, ὅς περ γένεσις πάντεσσι τέτυκται:

     Another might I at least [Hypnos “sleep”] of the gods everlasting
     Lull easily to sleep, and in that case streams
     Of river Oceanus who for all is even made the source;

4.  Hesiod through PDLP online v. supra Tufts University (CC) 2006 Hesiod, the Homeric Hymns and Homerica Cambridge MA USA, Harvard University Press / London, England UK, William Heinemann Ltd. © 1914 Theogony 240-242 c. 700 BC:

     Νηρῆος δ᾽ ἐγένοντο μεγήρατα τέκνα θεάων
     πόντῳ ἐν ἀτρυγέτῳ καὶ Δωρίδος ἠυκόμοιο,
     κούρης Ὠκεανοῖο, τελήεντος ποταμοῖο,

     And of Nereus, children lovely passing among goddesses
     Were in barren sea also of richly-haired Doris born;
     The daughter of Oceanus who is the river perfect:

etc.