The only free and comprehensive online etymological dictionary of the Spanish language
nacer (Verb) "to be born;" "to sprout"

10th cent. From Vulgar Latin *nascere, from Latin nasci 'id.' Old Latin gnasci. From Proto-Italic *gnāsk-e/o- 'id.' From Proto-Indo-European *ǵn̥h1-sḱe/o- 'id.' From *ǵenh1- "to produce," "to birth" and inchoative suffix *-sḱe/o- (see -ecer).

Romance: Western Vulgar Latin: Asturian nacer, Portuguese nascer, Galician nacer, Catalan nàixer, French naître, naitre, Italian nascere ; Eastern Vulgar Latin: Aromanian nascu, Aromanian naște ; Sardinian: naschere

Italic: Paelignian cnatois "to the son"

Indo-European: Celtic: Gaulish Cintu-gnātus "firstborn," Middle Welsh gnawt "daughter;" Germanic: Gothic -kunds "born of," Old Norse kundr "son," Old English cund "born," heofon-kund "heaven-born," "of divine descent;" Hellenic: Ancient Greek κασίγνητος (kasígnetos) "sibling," "cousin;" Indo-Iranian: Sanskrit jātá- "born man," Avestan zāta- "born"
nación f. (Noun) "nation"

15th cent. From Latin nationem, accusative of natio 'id.' Literally meaning "birth," as in one's birthland. From nasci "to be born" (see nacer).

Romance: Western Vulgar Latin: Portuguese nação, French nation, Italian nazione ; Eastern Vulgar Latin: Romanian națiune
nacional (Adjective) "national"

15th cent. From nación.

Romance: Western Vulgar Latin: Portuguese nação, French nation, Italian nazione ; Eastern Vulgar Latin: Romanian națiune
nada f. (Noun) "nothing"

11th cent. From Vulgar Latin nata "nothing," "little thing." Note an Old Spanish phrase cosa nada "little thing" (10th cent.). From the Latin phrase res nata "the question at hand" (but more literally, "the thing born"). For further etymology of nata, see nacer.

Note that Spanish de nada to answer to gratitude is mirrored in Catalan de res "you're welcome."
nadar (Verb) "to swim"

11th cent. From Latin natare 'id.,' from nare "to swim" with a frequentive suffix -tare (see note under faltar). Latin nare is from Proto-Italic *(s)nā-je/o- 'id.' From Proto-Indo-European *sneh2-i̯e/o- 'id.,' from the root *sneh2- of the same meaning.

Romance: Western Vulgar Latin: Asturian nadar, Portuguese nadar, Galician nadar, Catalan nedar, Italian nuotare ; Eastern Vulgar Latin: Aromanian anot, Romanian înota ; Sardinian: anatare

Indo-European: Celtic: Old Irish snaïd "to swim," Middle Welsh nawf "swimming," Middle Breton neuff 'id.;' Hellenic: Ancient Greek νήχω (nékho) "I swim;" Indo-Iranian: Sanskrit snātas "he bathes," Young Avestan fra-snaiia- "to wash;" Tocharian: B nāsk- "to swim"
nadie (Indefinite Pronoun) "no one"

12th cent. Old Spanish nadi. From Latin nati 'id.,' part of a larger phrase homines nati "no one" (but literally, "men born"). Listed by Roberts (2015) as from an ancient Latin expression homines nati non fecerunt "born men did not do it."
naranja f. (Noun, Adjective) "orange"

14th cent. The adjectival sense was a semantic extension of the fruit. From Arabic nāranj "orange," borrowed from Persian nārang 'id.,' itself borrowed from Sanskrit nāraṅga "orange tree." Of unknown origin.

Also the origin of Naranjo and Naranco, two mountain areas in Oviedo, probably so-called to reference their orange color. Also the mountain peakNaranjo/Naranco de Bulnes, a mountain peak in Asturias named by German geologist Wilhelm Schulz in 1855, probably based on its orange color (its original name is Picu Urriellu).

Romance: Western Vulgar Latin: Asturian naranxa, (Fernán Coronas) llaranxa, Portuguese laranja, Catalan taronja
nariz f. (Noun) "nose"

12th cent. Originally meaning "nostril." From Vulgar Latin *naricæ "nostrils," from Latin naris "nostril." From Proto-Italic *nās-i- 'id.' From Proto-Indo-European *Hneh2-s- 'id.' From a root *Hneh2- "to breathe" (whence alma).

Romance: Western Vulgar Latin: Asturian nariz, Portuguese nariz, Galician nariz, Catalan nariu, French narine, Italian narice ; Eastern Vulgar Latin: Aromanian nare, Romanian nară ; Sardinian: nare

Indo-European: Germanic: Old Norse nǫs "nostril," Old High German nasa "nose," Old Saxon nasa-druppo "cold," Old English nasu "nose" (English nose); Balto-Slavic: Church Slavic nosъ "nose," Russian nos' 'id.,' Czech nos 'id.,' Polish nos 'id.,' Slovene nọ̑s 'id.,' Old Prussian nozy 'id.,' Lithuanian nósis 'id.,' Latvian nãss 'id.;' Indo-Iranian: Sanskrit nas- "nose," Young Avestan nā̊ŋha "nose" (note that the word is in the dual)

The word naríz may in fact be a remnant of a Proto-Indo-European ablaut with a root-vowel *a. This is controversial at best, and not reflected in the etymologies in our dictionary, however the bare possibility demands mentioning. "Although the evidence is sparse, it appears that roots with a as fundamental vowel also ablauted. The root *sal- 'salt' had a zero-grad *sl̥-...; the root *nas- 'nose' has a lengthened-grade derivatives such as Latin nār-ēs and English nose, both from *nās-; and the root *laku- 'body of water' (Lat. lacus 'lake', Gk. lákkos 'pond') had an o-grade form *loku- that became Scottish Gaelic loch 'lake'. The view that roots in a ablauted is not universally accepted, but these forms are difficult to explain otherwise." ~ B. Fortson, Indo-European Language and Culture (2011)
natura f. (Noun) "nature"

12th cent. From Latin natura "nature," originally referring to the nature of a person. More literally rendered "concerning one's birth." From nasci "to be born" (see nacer).

Romance: Western Vulgar Latin: Portuguese natura, French nature, Italian natura ; Eastern Vulgar Latin: Romanian natură
natural (Adjective, Noun) "natural;" "native (person);" (m.) (temperment) "nature"

12th cent. An adjectival from Latin naturalis "natural," from natura "nature" (see natura).