The adverb of unpardonable: in a way that cannot be forgiven. It does two jobs. Most often it sits in front of an adjective and pushes it as far as it will go — unpardonably rude, unpardonably late, unpardonably slow, unpardonably careless. Here it works like 'terribly' or 'shockingly', but with a moral edge added: it does not just say 'very rude', it says 'rude in a way I refuse to excuse'. Its other job is to describe an action: 'He behaved unpardonably at the wedding.' Like the adjective it comes from, it is formal and a little literary — you meet it in novels and serious articles far more than in conversation — and it is often used with a wink about small faults, because a huge word on a tiny fault is funny. 'I was unpardonably late — three whole minutes.' Read the situation to know which one you are hearing. When people are being straightforward and everyday, they reach for 'inexcusably' or 'unforgivably', or simply 'there was no excuse for it'.

不可原諒地（常放在形容詞前加強語氣：unpardonably rude 無禮到不可原諒）。書面、略老派；口語多用 inexcusably／unforgivably。也常故意用來誇張小事。