NOUN (2)

1. abnormally small production of urine; can be a symptom of kidney disease or obstruction of the urinary tract or edema or an imbalance of fluids and electrolytes in the body;

2. production of an abnormally small amount of urine;

WordNet (r) 3.0 (2006):

oliguria
    n 1: abnormally small production of urine; can be a symptom of
         kidney disease or obstruction of the urinary tract or edema
         or an imbalance of fluids and electrolytes in the body
    2: production of an abnormally small amount of urine