[ˏdi:ik'seʃɚn]
v.
<美>出售,交换( 博物馆收藏品等)

[ verb ]
sell (art works) from a collection, especially in order to raise money for the purchase of other art works
<verb.possession>
The museum deaccessioned several important works of this painter

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]