ˌipsēˈdiksə̇t noun
( plural ipse dixits )
Etymology: Latin, literally, he himself said it, translation of Greek (Doric) autos epha; from the use of this expression by the Pythagoreans in reference to statements made by Pythagoras himself
: an assertion made on authority but not proved : dictum
has had a good many followers ready to accept his ipse dixit — D.W.Hering