occlusion

Imagine an eclipse: the moon blocks the sun's light. That simple picture captures the main idea of occlusion. It means that something is covered, closed off, or blocked, so that light, sight, air, liquid, or movement cannot pass through normally. A dentist may also talk about your occlusion, meaning the way your upper and lower teeth meet when you bite. If they do not meet in the right way, it is called a "malocclusion." In everyday terms, the word describes something being shut off, hidden, or blocked.

The word occlusion comes from the Latin "occludere," meaning "to shut up" or "to close off." At its heart, it describes a state in which something is closed, covered, or blocked.

You will often see the word in medicine and dentistry. Dental occlusion describes the way the upper and lower teeth come together when you bite. In medicine, a phrase like "coronary occlusion" refers to a blockage in an artery that stops blood from flowing properly. In meteorology, an "occluded front" forms when one weather front catches up to another and lifts the warm air above the ground.

The word also appears in technology and language studies. In computer graphics, occlusion describes one object blocking light or hiding another object from view, which helps create realistic shadows and depth. In linguistics, it can mean a complete closing of the mouth or air passage when certain sounds are made.

Whether it is a blocked artery, a weather pattern, teeth coming together, or a shadow in a 3D scene, occlusion always carries the idea of something being closed off or prevented from passing through.