Sorry, I Beg Your Pardon
noun, interjection
An honorable excuse is all I have, and that is no good. I'm sorry and I beg your pardon.
ごめん
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.
御免。流石に今日の今日で、空港まで迎えに行くのは無理だわ。もうちょっと早く言ってくれたらよかったのに。
Sorry. I won’t be able to pick you up at the airport today. You should’ve asked me earlier.