[1] : The Collaborative International Dictionary of English v.0.48

deaccession \deaccession\, de-accession \de-accession\v. t. de-
   + accession. ca. 1970.
   to sell artwork; -- used of sales of art by museums.

   note: the word appears to have been coined as a euphemism to
         avoid the negative connotations of the word "sell",
         particularly for works donated by benefactors. the
         practise is justified as a means of acquiring funds for
         purchase of more valuable artworks.
         wordnet 1.5 +pjc

[2] : WordNet (r) 2.0

deaccession
     v : sell art works from a collection, especially in order to
         raise money for the purchase of other art works; "the
         museum deaccessioned several important works of this
         painter"

Deaccession >> D Words
Deaccession, definition of term: Deaccession
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