I see the term co-morbidity used a lot, as in schizophrenia being often comorbid with bipolar, heart disease often co-morbid with diabetes, etc. In this context, morbid seems to mean a disease state--morbid obesity might be looked at as obesity that has progressed to the point where it constitutes a disease state, where it's a threat to health. Which is really just repeating what some others have said here. That said--language is for communication, and if the message received is too often not the message intended, I think there is an onus on the person speaking to make themself more clear to their audience.