Synonyms for Without basis:

• adj.

  •illogical (adjective)
  • unsound,
  • unconnected,
  • inconsistent,
  • cockeyed,
  • specious,
  • inconclusive,
  • incongruous,
  • nutty,
  • incorrect,
  • implausible,
  • unreasonable,
  • irrational,
  • wacky,
  • unscientific,
  • untenable,
  • fallacious,
  • preposterous,
  • mad,
  • unsubstantial,
  • inconsequent,
  • hollow,
  • groundless,
  • absurd,
  • senseless,
  • spurious,
  • fatuous,
  • sophistic,
  • faulty,
  • invalid,
  • screwy,
  • false.
  •unfounded (adjective)
  • unreal,
  • untrue,
  • baseless,
  • deceptive,
  • vain,
  • off-base,
  • uncalled-for,
  • unjustified,
  • gratuitous,
  • unsubstantiated,
  • fabricated,
  • untruthful,
  • idle,
  • bottomless,
  • unproven,
  • trumped up,
  • unwarranted,
  • Foundationless,
  • mendacious,
  • misleading.

• Other synonyms:

  •
  • unjustifiably.

Antonyms for Without basis:

• adj.

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