split-ring

plural split-rings · alternative split ring

1. A ring of metal wire looped almost twice about, as a keyring.

   Something was moving to and fro there, very quietly; every now and then it tapped against the wall, or started on its movements with a faint metallic ringing, like the movement of keys on a split-ring.

   1898, H.G. Wells, The War of the Worlds, London: William Heinemann, page 232

2. businessEither of a pair of concentric metallic rings with slits on opposite sides, used in split-ring resonators.