The only free and comprehensive online etymological dictionary of the Spanish language
dominio m. (Noun) "dominion"
15th cent. From Latin dominium 'id.,' from dominus "lord" (see dueño).
don m. (Noun) "gift"
From Latin donum 'id.' From Proto-Italic *dōno- 'id.' Reconstructable as either *doh3-no- or *deh3-no- 'id.' in Proto-Indo-European. From the root *deh3- "to give" (see dar).
Also the origin of the surname Dono, a name associated with men who have given much to local monastaries.
Indo-European
Romance
Portuguese dom, French don, Italian dono
Italic
Oscan dunúm, Umbrian dunum, Marsian donom, Volscan duno, Paelignian donom, Venetic donom
Celtic
Old Irish dán, Middle Welsh dawn
Balto-Slavic
Old Church Slavonic darъ, Lithuanian duõnis
Armenian
Armenian tur
Indo-Iranian
Sanskrit dā́na-
Basque
Old Gizpuzkoan doe "gift," a loanword from a Romance language pointing to a pre-form *done
Traditionally, a gift in Indo-European society demanded a gift in reciprocation. To give a gift without expectation of reward was special.
"A further question now arises: is there no simple expression for “gift” which does not call for a return? ... [Yes, as] there exists an Indo-European root, that of Latin do, dōnum, Greek dō̂ron." ~ E. Benveniste, Indo-European Language and Society (1973)
donar (Verb) "to donate"
10th cent. From Latin donare "to give," a verb from the noun donum "gift" (see don).
Indo-European
Romance
Portuguese doar, Catalan donar, French donner, Italian donare, Romanian dona
donde, dónde (Adverb) "where"
From 12th cent. Old Spanish de onde, from Latin de unde "from where."
dormir (Verb) "to sleep;" "to put to sleep"
12th cent. From Latin dormire 'id.' From Proto-Italic *dorm-je/o- 'id.' From Proto-Indo-European *dr̥m-i̯e/o- 'id.' From a root *drem- of the same meaning. A primary i̯e/o-present.
Indo-European
Romance
Astruian dormir, Portuguese dormir, Galician durmir, Catalan dormir, French dormir, Italian dormire, Romanian dormi, dormire, Aromanian dormu, Sardinian dormire
Balto-Slavic
Russian dremát', BCS drijèmati
Hellenic
Ancient Greek δαρθάνειν (darthánein)
-dor, -tor Noun-forming suffix indicating an occupation, agency or state of being.
From Latin -tor 'id.' From Proto-Italic *-tōr 'id.' From Proto-Indo-European *-tōr-s 'id.'
Indo-European
Romance
Asturian -teru, Portuguese -dor, Galician -dor, Catalan -dor, French -(t)eur, Italian -(t)ore, Aromanian -tor
As a general rule, Latin -tor became Spanish -dor, but t was preserved when preceded by a voiceless consonant (e.g., doctor).
dos (Cardinal Number) "two"
11th cent. From Latin duos, masculine accusative of duo 'id.' From Proto-Italic *duō 'id.' From Proto-Indo-European *du̯-o-h1 'id.' Notably, the word is in the dual form.
Variants
Old Spanish dues "two," from Latin duas, feminine accusative of duo
Indo-European
Romance
Astruian dos, Portuguese dois, Galician dous, Catalan dos, French deux, Italian due, Aromanian doi, dao, Romanian doi, Sardinian duos
Italic
Umbrian dur
Celtic
Old Irish dáu, Old Welsh dou 'id.,' Old Breton dou 'id.,' Old Cornish dow 'id.'
Germanic
Gothic twai, Old Norse tveir "Tyr," Old Saxon twēne, Old High German zwēne, Old English twēgen (English two)
Albanian
Albanian dy
Balto-Slavic
Old Church Slavonic dъva, Lithuanian , Old Prussian deiwas
Hellenic
Ancient Greek δύο (dyo)
Armenian
Armenian erku
Indo-Iranian
Sanskrit dváu "god," Young Avestan duua
Tocharian
A wu, B wi
droga f. (Noun) "drug"
15th cent. Borrowed from Old French drogue 'id.' An abbreviation of Middle Low German droge vat "dry barrel," which contained dried herbs.
-dromo (Suffix) "racecourse," "arena"
From Latin dromus 'id.' Borrowed from Ancient Greek δρόμος (drómos) 'id.,' derived from the verb δραμεῖν (drameîn) "to run." From Proto-Indo-European *drem- 'id.'
Indo-European
Indo-Iranian
Sanskrit dramati "he runs"
dueño (Noun) (m. & f.) "owner;" (m.) "master;" (f.) "mistress," "lady"
11th cent. From Latin dominus 'id.' From Proto-Italic *domo-no- "(person) of the house." Derived from *domo- "house." From Proto-Indo-European *dōm 'id.,' a root noun.
Also the origin of the surnames Dueñas, Doña, Doñamayor, and Doñas.
Indo-European
Romance
Portuguese dono, Catalan don, French dom, Italian don, Aromanian domnu, Romanian domn
Indo-Iranian
Sanskrit dámūnas- "lord of the house"
Cf. Basque dono- "saint," "holy," found in toponyms (e.g., Donostia), and was borrowed from Vulgar Latin *domnus "lord." Thus, dono- entered Basque during Latin's evolution into the Romance languages.