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

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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 In action, that sales pitch is mildly misleading, as visual downgrades from X to S also include reductions in shadow resolution, level-of-detail (LoD) scaling, ambient occlusion, and other features, depending on the game. Kyle Orland And Sam Machkovech, Ars Technica, "Xbox Series X/S vs. PlayStation 5: Our launch-month verdict," 22 Nov. 2020 That blistering frame rate comes at a cost of serious detail, from geometrical detail to ambient occlusion, from shadow resolution to texture pop-in, and from missing weather effects to missing crowds of people. Sam Machkovech, Ars Technica, "Xbox Series X unleashed: Our unrestricted preview," 15 Oct. 2020 The same cannot be said for the ho-hum CGI effects applied to droids, lizards, and speeder bikes, which all play out with a weird lack of ambient occlusion or shadow adjustment. Sam Machkovech, Ars Technica, "Mandalorian season 2 premiere: This is (still) the way," 30 Oct. 2020 While last year’s Modern Warfare stuck to ray tracing for shadows alone, limiting its visual punch, Black Ops Cold War will feature ray tracing for three different lighting effects: ambient occlusion, local shadows, and sun shadows. Brad Chacos, PCWorld, "Nvidia bundles Call of Duty: Black Ops Cold War with GeForce RTX 3080, 3090," 30 Oct. 2020 An occlusion occurs when cold air overtakes warm air near the center of a low-pressure system, pinching a region of warm air above the earth’s surface. Dennis Mersereau, Outside Online, "How to Read a Surface Weather Map," 15 Oct. 2020 Additionally, pop-in issues become much more apparent for both textures and shadows, and ambient occlusion is axed across the board. Sam Machkovech, Ars Technica, "DiRT 5 and our first Xbox Series X “enhanced” tests: 120Hz saves the uneven ride [Updated]," 11 Oct. 2020 While some games only dip their toes into real-time ray tracing with an effect or two, Fortnite is diving in, with ray traced reflections, shadows, global illumination, and ambient occlusion. Brad Chacos, PCWorld, "Fortnite flips RTX on September 17: Ray tracing, DLSS, and Nvidia Reflex," 15 Sep. 2020 In just the past few years, these APIs have become significantly more sophisticated, introducing features like realistic shadows, full-body motion capture, and occlusion. Samuel Axon, Ars Technica, "Google AR app lets you place prehistoric creatures, Apollo 11 in your room," 25 Aug. 2020

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.

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First Known Use of occlusion

circa 1645, in the meaning defined at sense 1

History and Etymology for occlusion

Latin occludere

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Time Traveler for occlusion

Time Traveler

The first known use of occlusion was circa 1645

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Cite this Entry

“Occlusion.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/occlusion. Accessed 2 Mar. 2021.

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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

More from Merriam-Webster on occlusion

Nglish: Translation of occlusion for Spanish Speakers

Britannica English: Translation of occlusion for Arabic Speakers

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