Русско-англо-русский юридический словарь

To adjourn an assembly sine die is to adjourn it for an indefinite period. (Wikipedia)

This Agreement is concluded for an indefinite period. (Agreement between the Government of the United Kingdom of Great Britain and Northern Ireland and the Government of the Kingdom of Belgium, concerning Immigration Controls on Rail Traffic between Belgium and the United Kingdom using the Channel Fixed Link )

This Agreement shall remain in force for an indefinite period of time but may be terminated by either Government upon giving notice in writing, through the diplomatic channel to the other Government, not less than six months before the end of any calendar year. (Agreement between the Government of the United Kingdom of Great Britain and Northern Ireland and the Government of Denmark on the Reciprocal Holding of Stocks of Crude Oil and/or Petroleum Products )

Although the IWC declared an indefinite moratorium on commercial whaling in 1986, some member countries continue to exploit loopholes in the rules. (BBC News)