What is a water closet commonly referred to as in plumbing standards?

A water closet is commonly referred to as a toilet or commode in plumbing standards. This term specifically denotes the fixture designed for the disposal of human waste, which typically includes a bowl and a flushing mechanism. The use of the term "water closet" has historical roots, originating from the practice of including a privacy partition for toilets in earlier designs. In modern terminology, "toilet" is widely recognized and used to identify this essential sanitary fixture in both residential and commercial settings.

In contrast, a sink refers to a basin typically used for washing hands, dishes, or food; a bidet is a fixture designed for personal hygiene after using the toilet; and a urinal is a plumbing fixture intended specifically for urination, generally used by males. Therefore, while these other options represent different types of plumbing fixtures, they do not correspond to the definition of a water closet.