British spelling variant of 'diarrheic'; relating to diarrhea using the alternative Greek spelling.
From British 'diarrhoea' (Greek 'diarrhoia') + suffix '-ic', preserving the traditional '-oe-' spelling pattern common in older English medical terminology.
If you see 'diarrhoeic' in modern text, it's almost certainly from a British or Commonwealth publication—it's a spelling fossil showing how English regions kept different versions of Greek-derived words.
Complete word intelligence in one call. Free tier — 50 lookups/day.