1. A movie made with a low or limited budget.
2. The phrase is more commonly misused to describe a movie of noticably poor quality.
3. It is rarely used to describe a movie with a low profit margin regardless of budget size, but I have heard it used this way occasionally.
1. "For a b movie, it had some pretty sweet visual effects."
2. "That might have been the worst movie I have ever seen. I wish the reviewer had mentioned it was a b movie"