in the global context, a specialised facility used for the detention of third-country nationals in accordance with national law, in the EU return context, a specialised facility to keep in detention a third-country national who is the subject of return procedures in order to prepare the return and / or carry out the removal process, in particular when: (a) there is a risk of absconding; or (b) the third-country national concerned avoids or hampers the preparation of return or the removal process