The term 'Goes Sour' can be summarized by two crossword solutions: 'Turns' (5 letters) and 'Rots' (4 letters). Both words refer to the process of food or other organic material decaying over time. When something 'turns, ' it changes from one state to another, such as from fresh to rotten. When something 'rots, ' it decomposes due to the action of bacteria and fungi. In both cases, the result is a sour smell and taste.