The exact meaning of occlude can depend upon its context. For example:
"an occluded artery" — closed or blocked, so no blood can flow through it
"occluded teeth" — position when the jaw is closed
"an occluded front" — when warm air is separated/blocked from the ground after meeting a cold front
"an occluded graphic" — a graphic that cannot be seen because it is blocked by an image between it and the eye
In dentistry, malocclusion is the misalignment of teeth and jaws. (mal- being a common prefix for bad.)
On land, meridional, a bispherical moon, revealed in imperfect varying phases of lunation through the posterior interstice of the imperfectly occluded skirt of a carnose negligent perambulating female, a pillar of the cloud by day.
Episode 17 — Ithaca (86% in)
There are no more uses of "occlude" in Ulysses by James Joyce.