Unbacked

adjective

1. Having no back.

   "an unbacked bench"

2. Not supported or backed up (by someone or something).
3. Having no (or few) backers.

   "a largely unbacked fundraising project"

4. Of an animal: never having been ridden or not accustomed to being ridden; not (currently) being ridden.
5. (holography) (of a plate) Not having an antihalation backing.