décommunautariser

Etymology
. See notes below to understand the difference of meaning of the word between the EU and Belgium.

Verb

 * 1)  to  communities, making them (progressively or not) lose their distinct identities to merge into a bigger one
 * 2)  to  competences from the European level to the state level
 * 3)  to transfer competences from the linguistic communities to the federal state

Usage notes
At first glance, one could wonder why in the European context, décommunautariser means "decentralise", but in Belgium it means "centralise". It is actually very simple.

Before 2009 and the Treaty of Lisbon, the European Union was organised in communities: the ECSC, Euratom, and the EEC (single market). The prefix being used to make antonyms and generally speaking meaning moving away from, the word evolved into "leaving, moving away from the European communities". And thus, decentralizing by giving competences to the member states making up the European Communities.

In Belgium, the communities are political areas based on the language spoken here (either French, Flemish, or German). Thus, by "moving away" from those communities, we can only go towards the central government: we.