IPA: //ʌnˈpɑːrdənəbl//
KK: /ʌnˈpɑːrdənəbl/
Something that cannot be forgiven or excused.
His actions were considered unpardonable by the community.
Unpardonable → It is formed from "un-" (meaning not) and "pardonable" (from Old French *pardonner*, meaning to forgive, combined with the suffix "-able" meaning capable of). The word "unpardonable" means not capable of being forgiven.
Think of 'not' ('un-') being added to 'forgivable' ('pardonable') — this helps you remember that unpardonable means something that cannot be forgiven.