The only free and comprehensive online etymological dictionary of the Spanish language
Juno f. (Noun) "Juno"
From Latin Iuno, the Roman goddess of marriage. According to de Vaan (2014), from a pre-form *iūn- "young." From Proto-Italic *juwen- 'id.,' the same source of joven.
junto (Adjective) "joined"
15th cent. From Latin iunctus 'id.,' from iungere "to join." From Proto-Italic *jung-e/o- 'id.' From Proto-Indo-European *i̯u̯-n-e-g- 'id.' A thematic verb (originally *i̯u̯-n-g-) derived from the root *i̯eu̯g- "to join," "to yolk" (see yugo) and the mysterious nasal-infix *-n- of unknown origin that formed the present tense in athematic verbs.
Indo-European
Romance
Asturian xuntu, Portuguese junto, Galician xunto, Catalan junt, French joint, Italian giunto
jurar (Verb) "to swear (an oath)"
12th cent. From Latin iurare 'id.' From Proto-Italic *jowes-ā-je 'id.' From the noun *jowes- "oath." From Proto-Indo-European *h2oi̯-u̯- "lifetime," "life force" (see joven).
Indo-European
Romance
Asturian xurar, Portuguese jurar, Galician xurar, Catalan jurar, French jurer, Italian giurare, Aromanian giur, Romanian jura, Sardinian giurài
Celtic
Old Irish uisse "fitting"
justicia f. (Noun) "justice"
12th cent. From Latin iustitia 'id.,' from iustus "just" (see justo).
Indo-European
Romance
Asturian xustica, Portuguese justiça, Galician xustiza, Catalan justícia, French justice, Italian giustizi, Romanian justiție
justo (Adjective) "just," "fair"
12th cent. From Latin iustus 'id.' From Proto-Italic *jowes-to- 'id.' Potentially a somewhat late adjective derived from *jowes- "oath." For a continued etymology, see jurar.
The word is the origin of a number of surnames, Justo, Justa, Justal, Juste, Justos, Justes. Also the origin of Justel, a small village in Leon.
Indo-European
Romance
Asturian xustu, Portuguese justo, Galician xusto, Catalan just, French juste, Italian giusto, Aromanian giustu, Romanian just, Sardinian giustu