occlusion

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The Word of the Day for December 5 is:

occlusion   \uh-KLOO-zhun\   noun
     1 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 

Example sentence:
     "Expect plenty of rain," warned the Midland Gliding Club Web site, "[from] 
a weakening occlusion ... close to northern Scotland."

Did you know?
     "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, 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.

*Indicates the sense illustrated in the example sentence.