"act or fact of being stopped up," 1640s, from Medieval Latin occlusionem (nominative occlusio), noun of action from past-participle stem of Latin occludere (see occlude). Dentistry sense "position of the two sets of teeth relative to each other when the mouth is closed" is from 1880.
occident
occidental
occipital
Occitan
occlude
occlusion
occlusive
occult
occultation
occultism
occupancy