unfounded

Adjective

1. Having no strong foundation; not based on solid reasons or facts.
   • an unfounded report; unfounded fears
   • […] my chiefest design ever since the seventeenth year of my age […] consisted in elaborating such demonstrations in Natural Philosophy, as might serve to unfold the natures of Beings in relation to the Art of Physick,...
   • […] such unfounded conjectures are best answered by neglect. - 1798, Thomas Robert Malthus, An Essay on the Principle of Population, London: J. Johnson, Chapter 11, p. 61, footnote:

   Synonyms: baseless groundless ungrounded idle footless unfounded unjustified unproved unproven unsubstantiated unsupported

2. Not having been founded or instituted.
   • Even the great world as yet undiscovered, the cities as yet unfounded, and the history as yet unwritten, are lost: fallen from the beginning. - 1980, Helen Louise Gardner, John Carey, English Renaissance studies, page...
3. Bottomless.
   • […] from them I go This uncouth errand sole, and one for all My self expose, with lonely steps to tread Th’ unfounded deep […] - 1667, John Milton, “Book II”, in Paradise Lost. […], London: […] [Samuel Simmons], and are...
   • He makes this Glob so spacious and fair Unfix’d, unprop’d, unfounded any where, Hang, like a Water-bubble in the Air. - 1685, William Clark, The Grand Tryal, or, Poetical Exercitations upon the Book of Job, Edinburgh,...