An Etymological Dictionary of Astronomy and Astrophysics

1. The process of occluding. Something that occludes.
   

   2. Phonetics: Closure at some point in the vocal tract that blocks the flow of air in the production of an oral or nasal stop (TheFreeDictionary.com).

   3. Chem.: An absorption process by which a substance adheres strongly to another.

See also: → occlude; → -tion.