The phrase "pass water" refers to urination, and there are several synonyms that can be used in its place. One common synonym is "pee," which is a more casual term. Another option is "urinate," which is a more formal term used in medical settings. "Piss" is a more vulgar and crass term. "Take a leak" is a colloquial term that is often used casually among friends. "Void" is a more clinical term and is commonly used by healthcare professionals. "Whizz" is a playful and fun term that is often used in informal settings. Finally, "go to the bathroom" can also be used as a more polite and discreet way of referring to urination.