unbased

un- +‎ based

unbased (comparative more unbased, superlative most unbased)

1. Without a sound basis; unfounded.
   • 1884, Popular Science (volume 25, number 19, page 290)

     To revive questions supposed to be long since settled, may be thought to need some apology; but there is a sufficient apology in the implication above made clear, that the theory commonly accepted is ill-based or unbased.

   • Louisa Burns, Studies in the osteopathic sciences (page 144)

     Such stumbling and unbased coincidences are often cited as indicative of some supernatural source of knowledge possessed by children and persons of the genius type; but if the unbased statements made of such persons the world over should be placed in one list, and the facts as later determined to be true should be placed in another, it seems that the laws of coincidence would govern the situation completely.

   • 2002, Eric Flint, ‎Richard Roach, Forward the Mage

     But the strangler's disquiet proved unbased. The snarl opened its jaws and Shelyid popped out, none the worse for wear.

• subdean