oc·​clu·​sion | \ ə-ˈklü-zhən How to pronounce occlusion (audio) \

Definition of occlusion

1 : the act of occluding : the state of being occluded: such as
a : the complete obstruction of the breath passage in the articulation of a speech sound
b : the bringing of the opposing surfaces of the teeth of the two jaws into contact also : the relation between the surfaces when in contact
c : the inclusion or sorption of gas trapped during solidification of a material
2 : the front formed by a cold front overtaking a warm front and lifting the warm air above the earth's surface

Keep scrolling for more

What Do the Words occlusion, recluse, seclusion, and exclude Have in Common?

Occlusion is a descendant of the Latin verb occludere, meaning "to close up." "Occludere" in turn comes from the prefix ob-, here meaning "in the way," and the verb claudere, meaning "to close or shut." "Occlusion" is one of many English terms derived from "claudere." Some others are "recluse," "seclusion," and "exclude." An occlusion occurs when something has been closed up or blocked off. Almost all heart attacks are the result of the occlusion of a coronary (heart) artery by a blood clot. When a person's upper and lower teeth form a "malocclusion," they close incorrectly or badly. An occlusion, or occluded front, happens when a fast-moving cold front overtakes a slow-moving warm front and slides underneath it, lifting the warm air and blocking its movement.

Examples of occlusion in a Sentence

Recent Examples on the Web Walk into your bedroom, and sunlight pouring through the windows has an apparent real-time shimmer on everything else (with ambient occlusion landing properly on objects outside the sun's direct reach). Sam Machkovech, Ars Technica, "Luigi’s Mansion 3 review: The most “Nintendo” game from Nintendo in years," 28 Oct. 2019 In addition to upgrades to ambient occlusion and shadow resolution, the trailer also shows a pretty dazzling overhaul to the game's water rendering system. Sam Machkovech, Ars Technica, "After canceling one upgrade, Minecraft gets another—and it’s Nvidia RTX exclusive," 19 Aug. 2019 Further Reading Apple’s watchOS 6 brings new apps (and various iPhone apps) to Watch ARKit itself will gain what's called people occlusion, which means that the framework will be able to obscure objects that a person walks in front of in real time. Samuel Axon, Ars Technica, "Apple shares its vision for macOS 10.15 Catalina: Cross-platform apps are key," 3 June 2019 Blocks gain extra depth and detail from normal maps, enabling shadows, lighting, specular reflectivity and ambient occlusion to further increase their fidelity and appearance. Brad Chacos, PCWorld, "Real-time ray tracing is coming to Minecraft on Windows 10, and it looks stunning," 19 Aug. 2019 Likewise, compressed sensing could be useful in combating occlusion in facial recognition systems — wearing sunglasses, for example, could be problematic if the eyes are a key variable in the analysis. Jennifer Ouellette, Quanta Magazine, "The Mathematical Shape of Things to Come," 4 Oct. 2013 Tubal Occlusion Also known as a tubal blockage, tubal occlusion is when an ovulated egg is unable to be fertilized by sperm or to reach the endometrial cavity or uterus. Jennifer Gerson, Marie Claire, "Why Can't I Get Pregnant?," 1 Oct. 2018 What's more, Project Stream's source servers appear to render the game at near-max PC settings, especially in crucial categories like ambient occlusion and shadow-map resolution. Sam Machkovech, Ars Technica, "Google’s Project Stream: That’s really a full Assassin’s Creed in my browser," 9 Oct. 2018 That paradox gets to the nub of this administration’s fraught relationship with ventilation and occlusion. Katy Waldman, Slate Magazine, "What “transparency” means to the Trump administration.," 24 July 2017

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'occlusion.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

See More

First Known Use of occlusion

circa 1645, in the meaning defined at sense 1

History and Etymology for occlusion

Latin occludere

Keep scrolling for more

Learn More about occlusion

Time Traveler for occlusion

Time Traveler

The first known use of occlusion was circa 1645

See more words from the same year

Listen to Our Podcast about occlusion

Statistics for occlusion

Last Updated

21 Dec 2019

Cite this Entry

“Occlusion.” The Merriam-Webster.com Dictionary, Merriam-Webster Inc., https://www.merriam-webster.com/dictionary/occlusion. Accessed 25 January 2020.

Keep scrolling for more

More Definitions for occlusion


oc·​clu·​sion | \ ə-ˈklü-zhən How to pronounce occlusion (audio) \

Medical Definition of occlusion

1 : the act of occluding or the state of being occluded : a shutting off or obstruction of something a coronary occlusion especially : a blocking of the central passage of one reflex by the passage of another
2a : the bringing of the opposing surfaces of the teeth of the two jaws into contact also : the relation between the surfaces when in contact
b : the transient approximation of the edges of a natural opening occlusion of the eyelids
3 : sorption especially : sorption of gases

Keep scrolling for more

More from Merriam-Webster on occlusion

Rhyming Dictionary: Words that rhyme with occlusion

Nglish: Translation of occlusion for Spanish Speakers

Britannica English: Translation of occlusion for Arabic Speakers

Comments on occlusion

What made you want to look up occlusion? Please tell us where you read or heard it (including the quote, if possible).


dull or mediocre

Get Word of the Day daily email!

Test Your Vocabulary

Intact Latin Quiz

  • roman tablet
  • What did focus mean in Latin?
Spell It

Can you spell these 10 commonly misspelled words?


Test Your Knowledge - and learn some interesting things along the way.

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!