imprecate (v.)

mid-15c., "a curse, cursing," from Latin imprecationem (nominative imprecatio) "an invoking of evil," noun of action from past participle stem of imprecari "invoke, pray, call down upon," from assimilated form of in- "into, in, within" (from PIE root *en "in") + precari "to pray, ask, beg, request" (from PIE root *prek- "to ask, entreat"). "Current limited sense is characteristic of human nature" [Weekley].

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.