expostulate (v.)

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.).

1530s, "nominate to a church office," from Medieval Latin postulatus, past participle of postulare "to ask, demand; claim; require," probably formed from past participle of Latin poscere "ask urgently, demand," from *posk-to-, Italic inchoative of PIE root *prek- "to ask questions." The meaning in logic, "lay down as something which has to be assumed although it cannot be proved" dates from 1640s, from a sense in Medieval Latin.

Proto-Indo-European root meaning "to ask, entreat." 

It forms all or part of: deprecate; deprecation; expostulate; imprecate; imprecation; postulate; pray; prayer; precarious; precatory; prithee.

It is the hypothetical source of/evidence for its existence is provided by: Sanskrit prasna-, Avestan frashna- "question;" Sanskrit prcchati, Avestan peresaiti "interrogates;" Latin precari "ask earnestly, beg, entreat;" Old Church Slavonic prositi, Lithuanian prašyti "to ask, beg;" Old High German frahen, German fragen, Old English fricgan "to ask" a question.