Urination is the noun for the act of passing urine — the event itself, not the liquid. Like urinate, it belongs to doctors, health articles, and forms; nobody says it over lunch. It shows up most often with a word describing something wrong: **frequent urination** (needing to go far too often, one of the classic warning signs of diabetes), **painful urination** (burning, usually an infection), **difficulty urinating**, or **blood in the urine**. It is uncountable — you talk about urination in general, not "a urination" or "three urinations". If you want the substance instead of the act, that is urine; if you want the everyday word for the act, that is "peeing" or just "going to the toilet".