Constriction, or narrowing, refers to the process where a passage or opening becomes smaller in diameter. This can occur in various contexts, such as in the human body, where blood vessels or airways may constrict due to factors like muscle contraction or inflammation. Constriction can affect the flow of blood or air, leading to potential health issues. In engineering and design, constriction can be applied to structures or systems to control the flow of materials or energy. For example, a nozzle in a spray bottle uses constriction to create a fine mist by narrowing the exit point, allowing for better control and efficiency in application.