Definition and background:
A set of two small disks of brass each held in one hand of the performer that are played by being struck together gently and allowed to vibrate. The antique cymbals are pitched percussion instruments and can be mounted as a chromatic set.
For more information on the music term "Antique cymbals" check out these other resources:
Wikipedia - Glossary of Musical Terminology
Virginia Tech Multimedia Music Dictionary
ORB -- Medieval Music Glossary