The antonyms for the term "won back" are many and varied. In fact, the opposite of winning something back could be described in a few different ways. One could argue that the antonym of winning something back is losing it, for example. Another antonym might be giving something up, relinquishing control or refusing to engage in competition to regain that which has been lost. Regardless of what antonym you choose, it is clear that the concept of winning something back implies a certain level of competition, determination, and persistence. The opposite, then, might suggest a more passive, resigned, or apathetic approach to the situation at hand.