oc·cul·ta·tion 
(ŏk′ŭl-tāshən)
(ŏk′ŭl-tāshən)n.
1. The act of occulting or the state of being occulted.
2. Astronomy
a. The passage of a celestial object across the line of sight between an observer and another celestial object, as when the moon moves between Earth and the sun in a solar eclipse.
b. The progressive blocking and unblocking of light or other electromagnetic radiation from a celestial source during such a passage: a lunar occultation of a quasar; a planetary occultation of a star.
c. An observational technique for determining the position or radiant structure of a celestial source undergoing such occultation or of the object causing the occultation.
3. Islam The temporary, supernatural removal of a holy person from visible existence, as Shiites believe is the case with the 12th imam.
[Middle English occultacion, from Latin occultātiō, occultātiōn-, from occultātus, past participle of occultāre, frequentative of occulere, to conceal; see OCCULT.]