Noun

1. Antiphon.
2. A choral or vocal composition, often with a religious or political even atheist lyric http://www.youtube.com/watch?v=wubIeiLs0qM.

   The school's anthem sang of its many outstanding qualities, and it was hard to keep a straight face while singing.

3. A hymn of praise or loyalty.

   The choir sang a selection of Christmas anthems at the service just before the big day.

4. A very popular song or track.
   • 2003, Peter Buckley, The rough guide to rock

     In May 2000, they even finally cracked the UK top ten when they teamed up with Paul Van Dyk on the trance anthem "The Riddle"...