Lewis Short
(adj.adv.) : irrĕfrāgābĭlis (inr-), e, adj. 2. inrefragor
* Irrefragable (eccl. Lat.), Pseudo ug. ad Fr. Erem. Serm. 35.—Hence, adv.: irrĕfrāgābĭlĭter, inviolably: Catholici dogmatis fundamenta observare, Ven. Fort. Vit. Hilar. 1 praef. 1.
Charlton T. Lewis, Charles Short, A Latin Dictionary