Occlusion is a term indicating that the state of something, which is normally open, is now totally closed.
- In medicine, the term is often used to refer to blood vessels, arteries or veins which have become totally blocked to any blood flow. For issues of artery occlusion, see stenosis, atheroma, and coronary catheterization.
- In dentistry, occlusion refers to the manner in which the teeth from upper and lower arches come together when the mouth is closed.
- In psychology, specifically memory research, occlusion is the phenomenon of items associated to the same cue as the target blocking the successful retrieval of that target, through strength dependent response competition. The tip-of-the-tongue phenomenon is an example of occlusion.
- In audiology, occlusion refers to the phenomenon that when persons with normal hearing close off the opening into the ear canal, the loudness of low pitched sounds (presented by bone conduction) increases.