A vaginal discharge can be caused by a variety of things like STDs, and yeast or bacterial infections. The discharge may change in color, have a foul or fishy smell, or be thick like cottage cheese. Discharge definition is — Define discharge: to relieve. Vaginal discharge is most often a normal and regular occurrence. However, there are certain types of discharge that can indicate an infection. Abnormal discharge may be yellow or green, chunky in consistency, or have a foul odor.