Word for "considered but not used"?

What is a good word that captures the concept of being considered, but not used?

For example:

"The scientists considered the implications of Charlie's proposed solution, but in the end tossed it in the bin with the other _____ ideas."


Solution 1:

Generically rejected works.

If there is a reason then:

  • infeasible
  • impractical
  • impossible
  • unconscionable