word-forming element, in English meaning usually "out of, from," but also "upwards, completely, deprive of, without," and "former;" from Latin ex "out of, from within; from which time, since; according to; in regard to," from PIE *eghs "out" (source also of Gaulish ex-, Old Irish ess-, Old Church Slavonic izu, Russian iz). In some cases also from Greek cognate ex, ek. PIE *eghs had comparative form *eks-tero and superlative *eks-t(e)r-emo-. Often reduced to e- before -b-, -d-, -g-, consonantal -i-, -l-, -m-, -n-, -v- (as in elude, emerge, evaporate, etc.).
It is the hypothetical source of/evidence for its existence is provided by: Sanskrit purtam "reward;" Hittite parshiya- "fraction, part;" Greek peprotai "it has been granted;" Latin partem (nominative pars) "a part, piece," portio "share, portion."
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Harper, D. (n.d.). Etymology of ex parte. Online Etymology Dictionary. Retrieved $(datetime), from https://www.etymonline.com/word/ex parte
Harper Douglas, “Etymology of ex parte,” Online Etymology Dictionary, accessed $(datetime), https://www.etymonline.com/word/ex parte.
Harper, Douglas. “Etymology of ex parte.” Online Etymology Dictionary, https://www.etymonline.com/word/ex parte. Accessed $(datetimeMla).
D. Harper. “Etymology of ex parte.” Online Etymology Dictionary. https://www.etymonline.com/word/ex parte (accessed $(datetime)).