silver jubilee 
noun
The twenty-fifth anniversary of a significant event.It is envisaged that a top level panel of judges will monitor and judge the competition, and the results will be announced next Spring to coincide with the club's silver jubilee special events programme....
- The joys of local soccer and many long lasting friendships developed in relation to it will be at the heart of the silver jubilee event.
- This year's event was particularly significant as it falls in the silver jubilee year of the Orkney Norway Friendship Association.