Polydipsia is the over frequent drinking of fluid. It is often associated with polyuria.
It is important with this symptom to get a good history of fluid intake. It is often seen in the recently retired, where the change in the habits of a lifetime may have resulted in their drinking, unawares, up to four or five litres of fluid a day, which is certainly going to result in urinary frequency. These patients should be asked to keep a fluid volume record, and then, when presented with the evidence told to reduce their fluid intake with specific instructions.
The associated symptom, thirst, is also very important in differentiating pathological and social causes.