The Collaborative International Dictionary of English v.0.48:
Diarrheal \Di`ar*rhe"al\, Diarrhoeal \Di`ar*rh[oe]"al\ a. (Med.) Of or pertaining to diarrhea; like diarrhea. DiarrheticWordNet (r) 3.0 (2006):
diarrheal adj 1: of or relating to diarrhea [syn: diarrheal, diarrhoeal, diarrhetic, diarrhoetic, diarrheic, diarrhoeic]