The only free and comprehensive online etymological dictionary of the Spanish language
pan (1) m. (Noun) "bread"

Late 11th cent. From Latin panis 'id.' From Proto-Italic *pā̆st-ni- 'id.' Of unknown origin.

Also the origin of the surnames Pan, Pane and Panes.

Romance: Western Vulgar Latin: Asturian pan, Portuguese pão, Galician pan, Catalan pa, French pain, Italian pane ; Eastern Vulgar Latin: Aromanian pãni, Romanian pâine ; Sardinian: pàne

Italic: Latin pastillum "loaf (for offering in sacrifice)" (pastnelo- "little cake")
Pan (2) (Surname)

From Nahuatl pantli "banner."
pantalón, pantalones (Noun) "pants"

C. 1800. Borrowed from French pantalon 'id.' Coined from Pantalone, a character from the Venetian commedia dell'arte, whose is typically portrayed with tight pants around his ankles. The name comes from Saint Pantaleone, a Nicomedian martyr of the 3rd and 4th centuries.
papá m. (Noun) "father"

18th cent. The accent on the second syllable may be due to French influence. From Latin papa 'id.' Probably of nursery origin; it is not farfetched to suggest a reduplication of Proto-Indo-European *ph2 "father." See also mamá, padre, madre.

Etruscan: Etruscan papa? "grandfather"

Indo-European: Hellenic: Ancient Greek πάππα (páppa) "father;" Armenian: (Alaškert) pab "father" (though probably a loan); Indo-Iranian: Persian bābā "father," Pahlavi pāpak 'id.;' Anatolian: Palaic papaš? "father" (but this points to *baba-)
papel m. (Noun) "paper"

14th cent. Borrowed from Old Catalan paper 'id.,' from Latin papyrus "papyrus," itself borrowed from Ancient Greek πάπῡρος (pápyros) 'id.' Of unknown origin but undoubtedly borrowed from another language. Beekes (2014) notes that -ῡρ- is a Pre-Greek suffix.

Romance: Western Vulgar Latin: Portuguese papiro, Catalan paper, French papier, Italian papiro ; Eastern Vulgar Latin: Romanian papir
papi (Noun) "daddy"

Colloquial term, either derived by redupilication of pa- in padre or romantic deformation of papá.
par m. (Noun, Adjective) "pair;" "equal"

12th cent. 'From Latin par 'id.' From Proto-Italic *parVs 'id.' Of unknown origin.

Romance: Western Vulgar Latin: Portuguese par, French pair, Italian paio

Italic: Umbrian pars "prescription"
para (1) (Preposition) "for"

12th cent. Old Spanish pora from por and a.
Para (2) (Toponym)

The name of a village in Burgos. Of uncertain origin.
parábola f. (Noun) "parable"

16th cent. borrowing from Ancient Greek παραβολή (parabolé) "comparison;" "parable." From πᾰρᾰ́ (pará) "beside" and βάλλειν (bállein) "to throw," combined for the sense of placing two things side-by-side for the purpose of comparison. For the continued etymology of πᾰρᾰ́, see relevant notes under pre-; for the etymology of βάλλειν, see diablo.

Romance: Western Vulgar Latin: Asturian pallabra, Portuguese palavra, Galician palabra, Catalan paraula, French palabre, Italian parola ; Sardinian: paragula