diuretic

adj. causing an increase in urination

n. substance which promotes urine flow

A diuretic is any drug that elevates the rate of bodily stool excretion (diuresis). There are several categories of diuretics. All diuretics increase the excretion of waste from the body, although each class of diuretic does so in a distinct way.
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Diuretic /di·uret·ic/ 1. pertaining to or causing diuresis. 2. an agent that promotes diuresis. high-ceiling diuretics , loop diuretics those [more]Diuretic - Community and Resources

Noun
1. any substance that tends to increase the flow of urine
(synonym) diuretic drug, water pill
(hypernym) drug
(hyponym) chlorthalidone, Hygroton, Thalidone

(n.)
A medicine with diuretic properties.
  

(a.)
Tending to increase the secretion and discharge of urine.