occlusion

occlusion is a Noun

Definition:

[1] The act of occluding, or the state of being occluded. Constriction and occlusion of the orifice. Howell.

[2] The transient approximation of the edges of a natural opening; imperforation. Dunglison. Occlusion of gases (Chem. & Physics), the phenomenon of absorbing gases, as exhibited by platinum, palladium, iron, or charcoal; thus, palladium absorbs, or occludes, nearly a thousand times its own volume of hydrogen, and in this case a chemical compound seems to be formed.