1. The act of occulting or the state of being occulted.
2. Astronomy.
   1. The passage of a celestial body across a line between an observer and another celestial object, as when the moon moves between Earth and the sun in a solar eclipse.
   2. The progressive blocking of light, radio waves, or other radiation from a celestial source during such a passage.
   3. An observational technique for determining the position or radiant structure of a celestial source so occulted: a lunar occultation of a quasar.

[Middle English occultacion, from Latin occultātiō, occultātiōn-, from occultātus, past participle of occultāre. See occult.]

The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.