ir·ref·ra·ga·ble 
(ĭ-rĕfrə-gə-bəl)
(ĭ-rĕfrə-gə-bəl)adj.
Impossible to refute or controvert; indisputable: irrefragable evidence.
[Late Latin irrefrāgābilis : Latin in-, not; see IN-1 + Latin refrāgārī, to oppose, resist; see bhreg- in the Appendix of Indo-European roots.]
ir·ref′ra·ga·bili·ty n.
ir·refra·ga·bly adv.