Colors can be measured and quantified in various ways; indeed, a person's perception of colors is a subjective process whereby the brain responds to the stimuli that are produced when incoming light reacts with the several types of cone cells in the eye.
unit of service. unit of service. any individual, family, aggregate, organization, or community given nursing care. The level at which service is delivered varies with the particular unit entity.
SI unit any unit of the International System of units (the metric system); see also si units. step-down unit a nursing unit designated to provide care for patients who are stable enough to be discharged from the intensive care unit but are not yet ready to be cared for on a medical-surgical unit.