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.
  •unfounded (adjective)
  • mendacious,
  • unproven,
  • Foundationless,
  • bottomless,
  • unwarranted,
  • uncalled-for,
  • deceptive,
  • untrue,
  • off-base,
  • vain,
  • idle,
  • untruthful,
  • unsubstantiated,
  • fabricated,
  • gratuitous,
  • trumped up,
  • unjustified,
  • misleading.

• Other synonyms:

  •adj.
  • illogical,
  • irrelevant,
  • meaningless,
  • unproved,
  • off the wall,
  • casuistic,
  • nonexistent,
  • self-contradictory,
  • sophistical,
  • unfounded,
  • not following,
  • without basis.
  •n.
  • 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.