ipse dixit

Definitions

1. A dogmatic and unproved proposition or dictum that is accepted solely on the authority of someone who is known to have asserted it.
   countable, rhetoric, uncountable
2. An authority who makes such an assertion.
   countable, uncountable

Examples

“To, avoid⟳, therefore, all Imputation of laying down a Rule⟳ for Poſterity, founded only on the Authority of ipſe dixit; for which, to ſay the Truth, we have⟳ not the profoundeſt Veneration; […]”

“Mr. Lincoln has not character enough for integrity and truth, merely on his own⟳ ipse dixit, to arraign President Buchanan, President Pierce, and nine Judges of the Supreme Court, not one of whom would be complimented by being put⟳ on an equality with him. There is an unpardonable presumption in a man putting himself up before thousands of people, and pretending that his ipse dixit, without proof, without fact, and without truth, is enough to bring⟳ down and destroy⟳ the purest and best of living men.”

CEFR level