What describes a drain from two or more fixtures connected to a single trap?

A drain from two or more fixtures that connects to a single trap is referred to as a continuous waste. This configuration allows multiple fixtures, such as sinks or laundry tubs, to share a common drainage outlet. The continuous waste setup is practical in plumbing because it reduces the need for multiple traps and simplifies the drainage system while maintaining proper drainage functionality.

In essence, continuous waste implies a direct pathway for waste to flow from multiple fixtures through one trap, thereby utilizing fewer materials and offering greater efficiency. This terminology is commonly used in plumbing to distinguish this specific arrangement from other types of drainage systems and configurations.

While continuous vent refers to a venting technique for maintaining harbored air pressure within a plumbing system, and drainage system generally refers to the complete network of pipes, traps, and fittings designed to convey wastewater away from fixtures, these terms do not specifically describe the scenario given in the question, which involves multiple fixtures connecting to a single trap. A dead end is a term often associated with a section of drainage that does not allow for continuous flow, and this does not apply to the question's context either.