Formal and quite literary. If a thought, feeling, or action is ignoble, it is low and small in a moral way — the kind of thing a person should be a bit ashamed of. Wanting your rival to fail, feeling secretly glad at bad news, staying quiet to save yourself trouble: these are ignoble. Notice it is not the same as 'evil' or 'cruel'. Ignoble is weaker and more about being unworthy — falling below the standard you would like to hold. Writers often use it about their own feelings, half-confessing: 'I felt an ignoble relief that it was not me.' It is the opposite of noble in the moral sense (fine, generous, honourable), not in the class sense — though the old class meaning did exist, so in a history book 'of ignoble birth' can mean 'not from a rich or important family'. You will mostly meet ignoble in novels, essays and speeches. In ordinary talk people just say 'petty', 'mean', or 'not a nice thing to feel'. It goes in front of nouns like thought, feeling, motive, act, end, defeat.

卑劣的、不光彩的（多半是指自己心裡那種說不出口的小心思，不是「邪惡」）