dummy

A dummy is a term with several related meanings describing a substitute, stand-in, or model used for demonstration, testing, or deception. The sense is transferable across fields: a dummy may stand in for a person, an object, or data while the real item is unavailable or unsafe to use.

In everyday language, "dummy" can describe a pacifier used by infants, especially in British English. It is a nipple-shaped object kept in the mouth to calm a baby.

In display and testing contexts, a dummy can be an imitation used for practice or demonstration, such as a mannequin in retail or a crash-test dummy used to study vehicle safety. In electronics and engineering, a dummy load or dummy resistor simulates a real electrical load for testing.

In statistics and data analysis, a dummy variable encodes a qualitative factor with numerical values, typically 0 or 1. "Dummy data" or "dummy text" (for example lorem ipsum) is placeholder information used to test software or layouts.

The term is also used colloquially to refer to a decoy or fake counterpart intended to mislead or occupy attention, as in pranks or simulations.