portio

Traditionally related to the same root as pars, possibly from Proto-Indo-European *perh₂- (“to sell”), which also gave the Ancient Greek πόρνη (pórnē, “prostitute”), and πέρνημι (pérnēmi, “to sell”).^[1]

De Vaan offers an alternative etymology where portiō would instead be a dissimilated and syncopated compound of prō +‎ ratiō: prō ratiōne > prōrtiōne > portiōne, an adverbial phrase from which the noun portiō would be back-formed.^[2] If this etymology is correct, portiō would be unrelated to pars.

• (Classical Latin) IPA^(key): [ˈpɔr.ti.oː]
• (modern Italianate Ecclesiastical) IPA^(key): [ˈpɔr.t̪͡s̪i.o]

portiō f (genitive portiōnis); third declension

1. share, part, portion
   • 27 BCE – 25 BCE, Titus Livius, Ab Urbe Condita 6.35.4:

     Creātīque tribūnī C. Licinius et L. Sextius prōmulgāvēre lēgēs omnēs adversus opēs patriciōrum et prō commodīs plēbis: ūnam dē aere aliēnō, ut dēductō eō dē capite, quod ūsūrīs pernumerātum esset, id, quod superesset, trienniō aequīs portiōnibus persolverētur.

     (please add an English translation of this quotation)

2. relation, proportion

Third-declension noun.

• portiōnālis
• portiuncula
• prōportiō

• pars

• “portio”, in Charlton T. Lewis and Charles Short (1879) A Latin Dictionary, Oxford: Clarendon Press
• “portio”, in Charlton T. Lewis (1891) An Elementary Latin Dictionary, New York: Harper & Brothers
• "portio", in Charles du Fresne du Cange’s Glossarium Mediæ et Infimæ Latinitatis (augmented edition with additions by D. P. Carpenterius, Adelungius and others, edited by Léopold Favre, 1883–1887)
• portio in Gaffiot, Félix (1934) Dictionnaire illustré latin-français, Hachette.
• William Dwight Whitney, Benjamin E[li] Smith, editors (1911), “portion”, in The Century Dictionary […], New York, N.Y.: The Century Co., →OCLC.