diarrhea
Concise Oxford English Dictionary © 2008 Oxford University Press:
diarrhoea /ˌdʌɪəˈrɪə/ (US diarrhea)
▶noun a condition in which faeces are discharged from the bowels frequently and in a liquid form.
– derivatives
diarrhoeal adjective,
diarrhoeic adjective.
diarrhoeal adjective,
diarrhoeic adjective.
– origin ME: via late L. from Gk diarrhoia, from diarrhein ‘flow through’.
'diarrhea' also found in these Oxford entries:

