Polydipsia is excessive thirst or excess drinking. The word derives from Greek πολυδίψιος (poludípsios) 'very thirsty', which is derived from Ancient Greek πολύς (polús) 'much, many' and δίψα (dípsa) 'thirst'. Polydipsia is a nonspecific symptom in various medical disorders. It also occurs as an abnormal behaviour in some non-human animals, such as in birds.
In Chinese medicine, excessive thirst denotes heat; thirst without the desire to drink is a sign of dampness or deficient yin.
Polydipsia is a symptom of diabetes.