1. (noun)occlusion closure or blockage (as of a blood vessel)
2. (noun)occluded front, occlusion (meteorology) a composite front when colder air surrounds a mass of warm air and forces it aloft
3. (noun)occlusion (dentistry) the normal spatial relation of the teeth when the jaws are closed
4. (noun)blockage, block, closure, occlusion, stop, stoppage an obstruction in a pipe or tube
"we had to call a plumber to clear out the blockage in the drainpipe"
5. (noun)blockage, closure, occlusion the act of blocking