The only free and comprehensive online etymological dictionary of the Spanish language
pero (Conjunction) "but," "yet"
12th cent. From Late Latin per hoc "therefore" (lit. "through that"). Used in the sense of "but" or "yet" in Latin in Iberia since the 6th cent. For the etymology of per, see por. Hoc is the neuter of hic; for the etymology of hic, see ahí.
Bilbao peró reflects an alternative accentuation in Vulgar Latin of per hóc instead of pér hoc
Ladino (Marruecos) peró, Catalan però (both from per hóc)
perrillo (1) m. (Noun) "trigger"
13th cent. Diminutive of perro, but the semantic evolution from "small dog" to "trigger" is obscure but the same animal metaphor occurs in gato ~ gatillo.
perrillo (2) m. (Noun) "small dog"
13th cent. Old Spanish perriello. Mostly fossilized in phrases perrillo de falda "lap dog" and perrillo de todas bodas "party animal." Diminutive of perro.
perro (Noun) "dog"
First attestation in the toponym Monte de Perra, 12th cent. Borrowed from a non-Indo-European language spoken in the Iberian peninsula (see Dworkin 2012). The word has no counterpart in Latin and highly localized cognates in the region suggest the word was inherited from a pre-Roman language. Corominas' (1991) theory that the noun derives from a common dog call among shepherds in Iberia, prr or brr, is not followed by specialists.
Vulgar use of perra "bitch," "slut" is common in other Western European languages (English bitch, French chienne, etc…).
Asturian perru "dog," Galician apurrar "to set dogs (on)," Portuguese berrar (of animals) "to cry," French (Hautes-Pyrénées) perrìta "sheep flock"
Originally, perro may have been a subset of all dogs (indicated by the native lexeme can). The word was in competition with can as late as the 16th century.
persona f. (Noun) "person"
Very early 12th cent. From Latin persona "human being," "mask." Borrowed from Etruscan phersu "mask."
Asturian persona, Portuguese pessoa, Galician persoa, Catalan persona, French personne, Italian persona, Romanian persoană
personal m. (Adjective, Noun) "personal;" "staff"
As a noun, from 19th cent. under influence from Galician. From Latin personalis 'id.,' from persona "person" (see persona).
Portuguese pessoal, French personnel, Italian personale, Romanian personal
pertenecer (Verb) "to pertain"
From Vulgar Latin *pertinescere 'id.,' from Latin pertinere "to relate" and inchoative suffix -escere (see -ecer). From per- "through" (see por) and tenere "to hold" (see tener).
Portuguese pertencer, Galician pertencer, Catalan pertànyer, Italian pertenere
pesar (1) (Verb) "to weigh"
12th cent. From Latin pensare 'id.' (see pensar).
Asturian pesar, Portuguese pesar, Galician pesar, Catalan pesar, French peser, Italian pesare, Romanian păsa, Sardinian pesare
pesar (2) m. (Noun) "regret"
12th cent. Deriving from the infinitive of pesar (1), as sadness and regret metaphorically weigh upon one's shoulders.
Most commonly found in the phrase en pesar de "in regret of," but literally "in weighing of."
peso (1) m. (Noun) "monetary unit"
Late 15th cent. Originally in peso de ocho "weight of eight," the name given to a Spanish thaler, or in English a pieces of eight. From peso (2).
Also the origin behind the names Pesoz, a town in Oviedo, and Ben Peso, a surname among Sephardic Jews.