excreting, excretion, voiding, elimination, evacuation - the bodily process of discharging waste matter

making water, passing water, wetting, leak - a euphemism for urination; "he had to take a leak"

lithuresis - passing small stones with the urine

nocturia, nycturia - excessive urination at night; especially common in older men

oliguria - production of an abnormally small amount of urine

peeing, pissing, pee, piss - informal terms for urination; "he took a pee"