An action or thing in which 'bad' is an intrinsic property. It is not bad because it hurts someone, and it is not bad because it keeps good from happening. It's just bad.
Some would say that cannibalism is inherently bad. Even if the person you are eating died from old age, asked to be eaten, as he knew it would save your life (which it does), and even if no-one who would be bothered by the idea of eating human meat will ever find out -- Even so, it's bad. (I personally don't believe this; it's just an example. You can eat me.)
Almost any 'Bad' can be said, by someone, to be inherently bad. Stealing, killing, lying, communism, you name it.
You might also hold that nothing is inherently bad; that things can only be bad in the sense that they are done or used in a 'bad' manner. One might hold that there are situations where anything, eating people, hurting people, killing people, etc., are all good (or at least okay, and not immoral).
Compare to Inherently Good.