You are right; chance isn't what is meant by "free will." But freedom of the will may be consistent with determinism, anyway. (Compatibilists argue that free will may be determination by some processes--e.g. one's own character traits--and not others--e.g. external coercion.)

Let me turn the tables on you and ask, "What is free will?" When people use this concept, they may have any of several different ideas in mind. Some people think of free will as freedom from external factors such as bribery or threats, some think of it as freedom from acting in accordance with one's own baser urges, some think of it as lack of determination (by the laws of nature/brain processes etc.) I think different sciences are relevant to each of these questions and that we can have evidence supporting or disconfirming claims about free will. Another way for you to think about your question: if there is no free will, what would you have lost?