What term refers to a complete lighting unit that includes a light source mounted and connected to a power supply?

The term that refers to a complete lighting unit, which includes a light source mounted and connected to a power supply, is "luminaire." A luminaire is essentially the assembly that holds the light source and supports all the necessary optics and electrical components for illumination. This term encompasses both the fixture and its parts, including the lamp (light source) and any necessary wiring or controls.

Other terms listed, such as "ballast," "fixture," and "illuminator," do not fully capture the complete concept of a luminaire. A ballast is a component specifically used in fluorescent lighting systems to regulate the current to the lamps, but it does not refer to the complete unit itself. "Fixture" is often used interchangeably with luminaire in casual language, but technically, it may not imply the inclusion of all necessary components such as the power supply. Lastly, "illuminator" is not a standardized term employed in the NEC context to describe a lighting unit. Thus, "luminaire" is the most accurate and appropriate term for a complete lighting unit in accordance with the NEC definitions.