Synonyms for Without foundation:

• adj.

  •illogical (adjective)
  • inconclusive,
  • false,
  • screwy,
  • invalid,
  • unsubstantial,
  • preposterous,
  • spurious,
  • unconnected,
  • cockeyed,
  • senseless,
  • irrational,
  • unscientific,
  • fallacious,
  • specious,
  • hollow,
  • inconsistent,
  • unreasonable,
  • incorrect,
  • faulty,
  • groundless,
  • unsound,
  • implausible,
  • inconsequent,
  • fatuous,
  • absurd,
  • incongruous,
  • wacky,
  • nutty,
  • untenable,
  • mad,
  • sophistic.
  •nonexistent (adjective)
  • empty,
  • blank,
  • baseless,
  • mythical,
  • dead,
  • ethereal,
  • hallucinatory,
  • Non-existent,
  • shadowy,
  • legendary,
  • Perished,
  • absent,
  • dreamy,
  • departed,
  • lost,
  • imaginary,
  • ungrounded,
  • negative,
  • passed on,
  • vague,
  • null and void,
  • tenuous,
  • hypothetical,
  • imponderable,
  • Gossamery,
  • insubstantial,
  • passed away,
  • defunct,
  • illusory,
  • extinguished,
  • dreamlike,
  • vaporous,
  • airy,
  • extinct,
  • unreal,
  • null,
  • void,
  • flimsy,
  • missing,
  • vacant,
  • gone,
  • imagined,
  • chimerical,
  • fancied,
  • few and far between,
  • immaterial.
  •Other relevant words: (adjective)
  • sophistical,
  • self-contradictory,
  • nonexistent,
  • without basis,
  • casuistic,
  • irrelevant,
  • meaningless,
  • illogical,
  • unfounded,
  • unproved,
  • off the wall,
  • not following.
  •unfounded (adjective)
  • mendacious,
  • unproven,
  • Foundationless,
  • bottomless,
  • unwarranted,
  • uncalled-for,
  • deceptive,
  • untrue,
  • off-base,
  • vain,
  • idle,
  • untruthful,
  • unsubstantiated,
  • fabricated,
  • gratuitous,
  • trumped up,
  • unjustified,
  • misleading.

• n.

  •Other relevant words: (noun)
  • Unsustained.

Antonyms for Without foundation:

• adj.

  • illogical
    meaningful, sensible, logical, reasonable, wise, true, correct, right, rational.
  • nonexistent
    real, actual, existing, existent.
  • unfounded
    justified, substantiated, supported, honest, called-for, founded, warranted, truthful, proven, genuine.