ANSWER
The word "jubilee" itself comes from the Hebrew "yobhel," or ram's horn trumpet, used to herald the arrival of a "jubilee" every fifty years. According to ancient Hebrew law, the "jubilee" was a year of renewal, when slaves were freed, prisoners released, and everyone got a fresh start. Translated through Greek and Latin into English, "jubilee" eventually came to mean any special anniversary. Today we use "Silver Jubilee" to mean the twenty-fifth anniversary of something, "Golden Jubilee" for the fiftieth, and "Diamond Jubilee" to signify either a sixtieth or seventy-fifth anniversary.
WHO GOT IT RIGHT: Robert Walker, Bob Milligan, Allan Christensen, Andie J, and Marc Quinlivan.