INEXPIABLE
inexpiable
(adjective) incapable of being atoned for
Source: WordNet® 3.1
Etymology
Adjective
inexpiable (comparative more inexpiable, superlative most inexpiable)
That cannot be expiated or atoned for; unforgivable.
Source: Wiktionary
In*ex"pi*a*ble, a. Etym: [L. inexpiabilis: cf. F. inexpiable. See In-
not, and Expiable.]
1. Admitting of no expiation, atonement, or satisfaction; as, an
inexpiable crime or offense. Pomfret.
2. Incapable of being mollified or appeased; relentless; implacable.
[Archaic] "Inexpiable hate." Milton.
They are at inexpiable war with all establishments. Burke.
Source: Webster’s Unabridged Dictionary 1913 Edition