irrefragable

adj.
Impossible to refute or controvert; indisputable: irrefragable evidence.

[Late Latin irrefrāgābilis : Latin in-, not; see in-¹ + Latin refrāgārī, to oppose, resist.]

irrefragability ir·ref'ra·ga·bil'i·ty n.
irrefragably ir·ref'ra·ga·bly adv.

(i-REF-ruh-guh-buhl)

adjective
Impossible to refute or dispute; incontrovertible.

Etymology
From Late Latin irrefragabilis, from Latin in- (not) + refragari (to oppose). Ultimately from Indo-European root bhreg- (to break) that's also the progenitor of words such as break, breach, fraction, fragile, fractal, infringe, and suffrage. Suffrage? Remember, a broken piece of tile was used as a ballot in earlier times.

Usage
"These issues were high on the agenda of the last American-Turkish talks. They were discussed thoroughly by the two sides many times and there were discords too. Thus George Bush won't give an irrefragable answer to these issues in Ankara." — Hakob Chakrian; US President in Ankara For the NATO Summit; AZG Armenian Daily (Yerevan, Armenia); Jun 26, 2004.

"Anderson quite clearly asserts 'there was irrefragable evidence of use of equine growth hormone by at least one cyclist at the AIS Del Monte'." — Inside the Shooting Gallery; The Sydney Morning Herald (Australia); Jul 10, 2004.

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1) impossible to refute: irrefutable
2) impossible to break