polydipsia
Concise Oxford English Dictionary © 2008 Oxford University Press:
polydipsia /ˌpɒlɪˈdɪpsɪə/
▶noun Medicine abnormally great thirst.
– origin C17: from Gk poludipsios ‘very thirsty’, based on dipsa ‘thirst’.
'polydipsia' also found in these Oxford entries:

