Inexcusable

(a.) Not justifiable; not admitting excuse; as, inexcusable folly.

Thesaurus Entries

blamable, blameworthy, censurable, impermissible, indefensible, inexpiable, intolerable, irremissible, reprehensible, unallowable, unconscionable, unforgivable, unjustifiable, unjustified, unpardonable, unpermissible, unreasonable, untenable, unwarrantable