A direct popular vote on a question of broad political importance, such as sovereignty or a ruler's mandate. Usage overlaps with 'referendum' and varies between countries and periods.
In more detail
In some legal systems a plebiscite is an advisory or authority-called vote, while a referendum concerns a legal text; in others the terms are reversed or interchangeable, so the national definition should be checked. The plebiscites held under the two Napoleons in France are classic historical examples, and critics saw them as tools of personal rule.