From Longman Dictionary of Contemporary Englishnot badnot badspokenGOOD ENOUGH used to say that something is good, or better than you expected‘How are you?’ ‘Oh, not bad.’That’s not a bad idea. →bad
Examples from the Corpus
not bad• "How are you?" "Oh, not bad."• Doing something you feel obligated to do is not bad.• Not an ale, but not bad.• All the news out of Texas is not bad.• But for all that, you are not bad.• It was not bad at all ... Emma: Not bad at all!?• But for an afternoon's work, not bad at all.• "What was the food like?" "Oh, not bad - better than last time."• "How was the exam?" "Oh, not too bad. I think I passed."• That's not a bad idea.• You know, that's not a bad idea.• A sweetheart, this little lady, not badlegs either.• Not bad, not bad I've been sorting out my counciltaxGeorge.