Sentence:  Some E.U. policymakers have argued for a “<WSD>flextension</WSD>” that would set a date for Britain's E.U. exit far in the future but allow Britain to leave as soon as it comes up with a viable plan. 
Meaning of the word marked with <WSD> tags:  The extension of a deadline that allows a flexible final date (originally used to refer to Brexit, but subsequently extended to other contexts).