Plain English Meaning
Very bright airport lights, used where normal lights would be hard to see, such as in fog, rain, or strong sunlight. The brightness can usually be turned up or down.
Full Definition
A category of airport lighting designed to be visible in daylight, bright sunlight, or reduced-visibility conditions, typically used for runway edge lights, approach lights, and obstruction lights at busier or instrument-equipped airports. The intensity is adjustable in steps and is often pilot-controlled or controller-controlled to match prevailing conditions.