unridered

adjective2

1. •
   Of an animal: without a rider; unridden.

   • An oncoming tree limb hooks his knees and he swings up and around as his horse races on unridered. — 2016
2. •
   Without a rider (supplementary clause).

   • […] the unridered insurance benefits affecting the unit employees were in effect at the time […] — 1967