occlusion Obstruction or a closure of hollow organ, passageway or vessel; also the transient approximation of the edges of a natural opening; imperforation. The act of closure or the state of being closed; an obstruction; the relationship between all of the components of the masticatory system in normal function, dysfunction, and parafunction; momentary complete closure of some area in the vocal tract, causing stoppage of the breath and accumulation of pressure. http://purl.obolibrary.org/obo/NCIT_C50678 changing topology