The only free and comprehensive online etymological dictionary of the Spanish language
volar (Verb) "to fly;" "to blow up"
13th cent. From Latin volare "to fly." From Proto-Italic *gwela-je/o- 'id.' From Proto-Indo-European *gwelh1-i̯e/o- "to raise an arm."
Indo-European
Romance
Catalan voler, French vouloir, volition, Italian volere, Aromanian voi, Romanian vrea, Sardinian bòliri
Celtic
Old Irish a-t-baill "to die"
Hellenic
Ancient Greek βάλλειν (bállein) "to hit by throwing"
Indo-Iranian
Sanskrit gari "to raise an arm (in order to strike)"
voluntad f. (Noun) "will"
10th cent. From Latin voluntatem, accusative of voluntas 'id.' From velle "to desire." From Proto-Italic *wel-e/o- 'id.' From Proto-Indo-European *u̯elh1- "to pursue."
Indo-European
Romance
Portuguese vontade, Catalan voluntat, French volonté, Italian voluntà, Sardinian bolontade
Germanic
Gothic waljan "to choose," Old Norse velja "to choose," Old High German wellan "choice," Old Saxon wellian 'id.,' English to will
Balto-Slavic
Old Church Slavonic velěti "to want," Russian velét' 'id.,' Czech veleti "to command," Slovene velẹ́ti "to want," Lithuanian vélti "to allow"
Hellenic
Ancient Greek λῆμα (lêma) "will"
Indo-Iranian
Sanskrit vr̥ṇīté "he chooses," Old Avestan var- "to choose"
volver (Verb) "to return"
12th cent. From Latin volvere "to turn." From Proto-Italic *welo-e/o- "to cause to go around." From Proto-Indo-European *u̯el-u̯- "to wind;" "to cover."
Indo-European
Romance
Portuguese volver, Galician volver, Catalan vogir, Italian volgere, Aromanian volbu, Romanian holba
Celtic
Old Irish fillid "to bend," Middle Breton goalenn "green twig"
Germanic
Gothic walwjan "to revolve," Old English wealwian 'id.'
Balto-Slavic
Old Church Slavonic valiti "to roll"
Hellenic
Ancient Greek εἰλύω (eilyo) "I wind"
Armenian
Armenian egel "he turned"
Tocharian
A walyi "worms," B wäl- "to curl"
vos (Personal Pronoun) "you"
12th cent. Originally meaning (pl.) "you." The creation of vosotros (12th cent.) as an emphatic form of vos gradually led to vos being restricted to the singular sense, beginning in the 15th cent. From Latin vos 'id.' From Proto-Italic *wōs 'id.' From Proto-Indo-European *u̯ōs "to you," accusative of *i̯uH.
Indo-European
Romance
Portuguese vós, Galician vós, Catalan vós, French vous, Italian voi, Aromanian voi, Romanian voi
vosotros (Personal Pronoun) (pl.) "you"
12th cent. Originally an emphatic form of vos. From vos and otro.
Indo-European
Romance
Galician vosoutros, Catalan vosaltres, French vous autres, Italian voialtri
voy, vaya, va-, vaya- Present and imperative conjugation forms in verb ir.
Old Spanish vo, vaya, va-, vaya- respectively, except Spanish vamos and vais were drawn from Old Spanish vamos, 1st person plural present subjunctive, and vades, 2nd person plural present subjunctive, which replaced Old Spanish imos and ides in the 16th cent. through a process of regularization. However, the archaic sense of vamos is preserved as the imperative, which was left unaffected by this development.

All forms are from Latin vadere "to go," "to hurry." Latin vadere is from Proto-Italic *wāþ-e/o- 'id.' A thematic present from Proto-Indo-European *u̯eh2dh- 'id.'
The evolution of this verb into Spanish is curious. Evidently, after the interior -d- was lost in Vulgar Latin, stress was maintained on the initial vowel that made it resistant to regular phonological changes in early Spanish (e.g., Latin vadis "you go" yields vas and not **ves) (see also Penny 2002).

Subjunctive forms were remodeled after other verbs ending in -aya (cf. haber).

For the evolution of Old Spanish vo to modern Spanish voy, see -oy.
voz f. (Noun) "voice"
12th cent. From Latin vocem, accusative of vox 'id.' From Proto-Italic *wōkws 'id.' From Proto-Indo-European *u̯ōkw-s
Indo-European
Romance
Asturian voz, Portuguese voz, Galician voz, Catalan veu, French voix, Italian voce, Aromanian boatsi, Romanian voce, Sardinian boghe
Italic
Umbrian suboco "invocation" (lit. 'low-voice')
Hellenic
Ancient Greek ὀπ- (óp-) "voice"
Indo-Iranian
Sanskrit vā́k "voice," Old Avestan vāxš 'id.'
Tocharian
A wak "voice," wek 'id.'
vuelo m. (Noun) "flight"
14th cent. From volar.
vuestro (Possessive Pronoun) "your"
12th cent. From Latin vostrum, accusative of voster 'id.' From Proto-Italic *wos-tero- 'id.' From Proto-Indo-European *u̯s-tero- 'id.'
Indo-European
Romance
Asturian vuestru, Portuguese vosso, Galician voso, Catalan vostre, French votre, Italian vostro, Aromanian vostru, Romanian vostru, Sardinian bostru
vulgar (Adjective) "vulgar;" "common"
15th cent. From Latin vulgaris "common," "plain," from vulgus "common people," "crowd" (see vulgo).
Indo-European
Romance
Portuguese vulgar, Galician vulgar, Catalan vulgar, French vulgar, Italian volgare, Romanian vulgar