"invested with, having, or bestowing full power," 1640s, from French plénipotentiaire and directly from Medieval Latin plenipotentiarius "having full power," from Late Latin plenipotens, from Latin plenus "complete, full" (from PIE root *pele- (1) "to fill") + potentem "powerful" (see potent). As a noun from 1650s, "person invested with full powers to transact any business," especially with reference to an ambassador to a foreign court or government, given full power to negotiate a treaty or transact other business.
Proto-Indo-European root meaning "powerful; lord."
It forms all or part of: bashaw; compos mentis; despot; hospodar; host (n.1) "person who receives guests;" idempotent; impotent; omnipotent; pasha; plenipotentiary; posse; possess; possible; potence; potency; potent; potentate; potential; potentiate; potentiometer; power; totipotent.
It is the hypothetical source of/evidence for its existence is provided by: Sanskrit patih "master, husband;" Greek posis, Lithuanian patis "husband;" Latin potis "powerful, able, capable; possible."
It forms all or part of: accomplish; complete; compliment; comply; depletion; expletive; fele; fill; folk; full (adj.); gefilte fish; hoi polloi; implement; manipulation; nonplus; plebe; plebeian; plebiscite; pleiotropy; Pleistocene; plenary; plenitude; plenty; plenum; plenipotentiary; pleo-; pleonasm; plethora; Pliocene; pluperfect; plural; pluri-; plus; Pollux; poly-; polyamorous; polyandrous; polyclinic; polydactyl; polydipsia; Polydorus; polyethylene; polyglot; polygon; polygraph; polygyny; polyhedron; polyhistor; polymath; polymer; polymorphous; Polynesia; polyp; Polyphemus; polyphony; polysemy; polysyllabic; polytheism; replenish; replete; supply; surplus; volkslied.
It is the hypothetical source of/evidence for its existence is provided by: Sanskrit purvi "much," prayah "mostly;" Avestan perena-, Old Persian paru "much;" Greek polys "much, many," plethos "people, multitude, great number," ploutos "wealth;" Latin plus "more," plenus "full;" Lithuanian pilus "full, abundant;" Old Church Slavonic plunu; Gothic filu "much," Old Norse fjöl-, Old English fela, feola "much, many;" Old English folgian; Old Irish lan, Welsh llawn "full;" Old Irish il, Welsh elu "much."