The only free and comprehensive online etymological dictionary of the Spanish language
aya f. (Noun) "governess"
15th cent. From Latin avia "grandmother." From Proto-Italic *awīā 'id.' From Proto-Indo-European *h2eu̯-i̯h2- 'id.' From *h2eu̯h2- "grandparent" (see also ayo).
Indo-European
Romance
Portuguese aia, Catalan aia
Hellenic
Ancient Greek αἶα (?) (aía) "grandmother"
In the masculine, Latin avus "grandfather" took a different sense. See ayo.
The -i- in avia is a relic from a devi-type inflection in Proto-Indo-European, vanishingly rare in the Italic language family.
ayer m. (Noun, Adverb) "yesterday"
Early 14th cent. Old Spanish yer. From Latin heri 'id.,' with a- added via analogy with other adverbs. From Proto-Italic *χes-i 'id.' From Proto-Indo-European *ǵh-di̯-es "yesterday," but originally "at that day." From *ǵh-e/o- "this," "that" (see aquí, acá) and *di̯- "day" (see día).
Indo-European
Romance
Asturian ayeri, Old Portuguese eire, Catalan ahir, Occitan ièr, French hier, Italian ieri, Dalmation jere, Aromanian a(i)eri, Romanian ieri
Celtic
Old Irish indé, Middle Breton doe, Old Cornish doy
Germanic
Gothic gistra-dagis "tomorrow," Old Norse í gær "yesterday," "tomorrow," Old High German gestaron, Old English geostran-dæg (English yesterday)
Albanian
Albanian dje
Hellenic
Ancient Greek χθές (khthés)
Indo-Iranian
Sanskrit hyás
ayo m. (Noun) "tutor"
11th cent. From Latin avus "grandfather." From Proto-Italic *awo- 'id.' From Proto-Indo-European *h2eu̯h2- "grandparent."
Indo-European
Romance
Portuguese avô, Galician avó, Catalan avi, Occitan ièr, Italian avo, Dalmation jere, Romanian auș, Sardinian abu
Celtic
Old Irish aue "grandson," Middle Welsh ewythr "uncle," Middle Breton eontr 'id.'
Germanic
Gothic awo "grandmother," Old Norse ái "great-grandparent"
Albanian
Albanian dje
Balto-Slavic
Old Church Slavonic ujь, Old Prussian awis "uncle," Lithuanian avýnas "maternal uncle"
Armenian
Armenian haw
In the feminine, Latin avia "grandmother" took a different sense. See aya.
ayuda f. (Noun) "help"
12th cent. From ayudar.
Indo-European
Romance
Asturian ayuda, Portuguese ajuda, Galician axuda, Catalan ajuda, French aide
ayudar (Verb) "to help"
12th cent. From Latin adiutare 'id.,' a verb formed from adiuvare "to assist," from ad- "towards" (see a(d)-) and iuvare "to help." From Proto-Italic *ijow- 'id.' From Proto-Indo-European *h-h1eu̯H-(e/o)- 'id.'
Indo-European
Romance
Asturian ayudar, Portuguese ajudar, Galician axudar, Catalan a(j)udar, French aider, Italian aiutare, Aromanian agiutari, Romanian ajutare
Celtic
Old Irish conoí
Indo-Iranian
Sanskrit ávati, Old Avestan auuāmī
As Latin evolved into Spanish, -d- disappeared when it was intervocalic and along a morpheme border (compare Latin adunare "to join" > Spanish aunar).
ayunar (Verb) "to fast"
13th cent. From Vulgar Latin iaiunare 'id.' From Latin iaiunus "fasting." From Proto-Italic *jagjūno- "sacrificial." Animal sacrifices were performed on an empty stomach. From Proto-Indo-European *Hi̯eh2ǵ-i̯u- 'id.' From a root *Hi̯eh2ǵ- "to sacrifice."
Indo-European
Romance
Asturian ayunar, Romanian ajuna
Hellenic
Ancient Greek ἁγνός (agnós) "holy"
Indo-Iranian
Sanskrit yájati "to sacrifice," Avestan yaza- "to worship"
-azgo Suffix indicating the relationship or position of the noun.
Akin to English -ship. From Latin -aticus, an adjective-forming suffix. From -atus "like" (see -ado) and -icus, an adjective-forming suffix (see -ico).
Indo-European
Romance
Italian -atico, Aromanian -atic, Romanian -atec
-azo Suffix augmenting a noun, meaning a hit or strike, or indicating brevity.
From Latin -aceus a relational suffix. From -ax "inclination" and -eus, indicating characteristics of the noun.
Indo-European
Romance
French -asse, Italian -accio
azúcar m. & f. (Noun) "sugar"
13th cent. From Andalusian Arabic assúkkar 'id.,' itself borrowed from Greek σάκχαρι (sákhari) 'id.,' earlier σάκχαρ (sákkhar). A loan from an Indic source, perhaps Pali sakkharā- 'id.' From Sanskrit śárkarā- 'id.'
azul m. (Adjective, Noun) "blue"
10th cent. Old Spanish azur. Originally referring to lapis lazuli and the color of dye the stone makes. Borrowed from Andalucian Arabic *lāzūrd of Arabic lāzuward "lapis lazuli," itself borrowed from Persian lâjvard 'id.'
"Latin lacked a basic term for 'blue,' using caerulus 'sky-colored' as the label for that color, a word that failed to survive in Romance languages, in all of which the basic term for 'blue' is a borrowing... There seems to be no way of knowing how speakers expressed the concept of 'blue' prior to the integration of azul into the lexicon." ~ S. N. Dworkin, A History of the Spanish Lexicon: A Linguistic Perspective (2012)