uninventable

That cannot be invented.

Adjective

  1. That cannot be invented.
    • The professor claimed that a time machine was uninventable, since nobody can travel faster than the speed of light.
    • Tulloch now and again touched off some inimitable phase of life or told an uninventable anecdote of native character […] - 1923, Ernest Bramah, The Eyes of Max Carrados:

Origin

From un- + inventable.