毛病 (máo bìng): fault, trouble, illness

My old car broke down again; this morning it wouldn't start no matter what, so I had to take the subway to work.

He has had a bad habit of being a picky eater since childhood; he won't eat a single bite of vegetables, and his mother is very troubled by it.

After a careful examination, the doctor said there's something wrong with my father's heart and he needs to stay in the hospital for a few days of observation.

The problem with this air conditioner is that it's too noisy; at night it's so loud that people can't sleep, so we're planning to get someone to fix it.

He is very capable at work, but he has one fault: he is always late for meetings, which makes his colleagues quite dissatisfied.