Source : Webster's Revised Unabridged Dictionary (1913)

Diarrheal \Di`ar*rhe"al\, Diarrhoeal \Di`ar*rh[oe]"al\ a. (Med.)
   Of or pertaining to diarrhea; like diarrhea.

Source : WordNet®

diarrheal
     adj : of or relating to diarrhea [syn: {diarrhoeal}, {diarrhetic},
            {diarrhoetic}, {diarrheic}, {diarrhoeic}]