Etymology
1. Originally an i-stem (*nāvis; compare dialectal nāvs) changed by analogy into a 5th-declension e-stem; from Proto-Balto-Slavic *nā́ˀwis, from Proto-Indo-European *neh₂wis, from the stem *neh₂w- (“death”). There is also a stem *néh₂us (“boat, ship”) (compare Latin navis, Ancient Greek ναῦς (naûs), Sanskrit नाव (nāva), Proto-Scythian *nā́w (“boat, ship”), Tajik нов (nov, “gutter”), Norwegian Bokmål nu (“hod, trough”). It is possible that these two *neh₂w-'s were originally one stem, with the meaning “timber, tree” (compare Sanskrit वन (vana, “timber, tree, forest”), apparently with metathesis of v and n), from which the meaning would change in two ways: on the one hand, “timber, tree” > “dug-out tree” > “boat, ship”, and, on the other hand, “timber, tree” > “tree stump, dead tree” > “dead body; death.”
2. Cognates include Lithuanian nõvis (“death”), nõvė (“slaughtering, killing; unknown disease; yoke; coercion”), Old Prussian nowis (“body, flesh”), Russian dialectal навей (navej), навь (navʹ), навье (navʹje, “corpse, dead body”), Czech archaic nav (“tomb, hell, beyond”), Gothic 𐌽𐌰𐌿𐍃 (naus, “dead body, corpse”), genitive 𐌽𐌰𐍅𐌹𐍃 (nawis), Breton naoun (“hunger”) (< Proto-Celtic *nāunyā). See: Latin Nouns '
navis', Ancient Greek Nouns '
ναῦς', Norwegian Bokmål Nouns '
nu', Gothic Nouns '
𐌽𐌰𐌿𐍃'.