Word Study
groundless
CIDE DICTIONARY
groundless, a. [AS. grundleás bottomless.].
Without ground or foundation; wanting cause or reason for support; not authorized; false; baseless; as, groundless fear; a groundless report, rumor, or assertion.
OXFORD DICTIONARY
groundless, adj. without motive or foundation.
Derivative
groundlessly adv. groundlessness n.
Etymology
OE grundleas (as GROUND(1), -LESS)
THESAURUS
groundless
baseless, bottomless, built on sand, chimerical, empty, flimsy, gratuitous, hypothetical, idle, ill-founded, illusory, imaginary, inconclusive, indecisive, not following, not proved, not well-founded, speculative, suppositional, tenuous, unascertained, unattested, unauthenticated, unbased, uncalled-for, uncertified, unconfirmed, uncorroborated, undemonstrated, undetermined, unestablished, unfixed, unfounded, ungrounded, unjustifiable, unjustified, unproved, unproven, unreasonable, unsettled, unshown, unsound, unsubstantiated, unsupportable, unsupported, unsupported by evidence, unsustainable, unsustained, untenable, untested, untried, unvalidated, unverified, unwarranted, vain, without basis, without foundation, without groundsROGET THESAURUS
groundless
Unsubstantiality
N unsubstantiality, insubstantiality, nothingness, nihility, no degree, no part, no quantity, no thing, nothing, naught, nil, nullity, zero, cipher, no one, nobody, never a one, ne'er a one, no such thing, none in the world, nothing whatever, nothing at all, nothing on earth, not a particle, all talk, moonshine, stuff and nonsense, matter of no importance, matter of no consequence, thing of naught, man of straw, John Doe and Richard Roe, faggot voter, nominis umbra, nonentity, flash in the pan, vox et praeterea nihil, shadow, phantom, dream, ignis fatuus, such stuff as dreams are made of, air, thin air, vapor, bubble, baseless fabric of a vision, mockery, hollowness, blank, void, inanity, fool's paradise, unsubstantial, baseless, groundless, ungrounded, without foundation, having no foundation, visionary, immaterial, spectral, dreamy, shadowy, ethereal, airy, cloud built, cloud formed, gossamery, illusory, insubstantial, unreal, vacant, vacuous, empty, eviscerated, blank, hollow, nominal, null, inane, there's nothing in it, an ocean of dreams without a sound.& Sophistry
N intuition, instinct, association, hunch, gut feeling, presentiment, premonition, rule of thumb, superstition, astrology, faith (supposition), sophistry, paralogy, perversion, casuistry, jesuitry, equivocation, evasion, chicane, chicanery, quiddet, quiddity, mystification, special pleading, speciousness, nonsense, word sense, tongue sense, false reasoning, vicious reasoning, circular reasoning, petitio principii, ignoratio elenchi, post hoc ergo propter hoc, non sequitur, ignotum per ignotius, misjudgment, false teaching, sophism, solecism, paralogism, quibble, quirk, elenchus, elench, fallacy, quodlibet, subterfuge, subtlety, quillet, inconsistency, antilogy, a delusion, a mockery, and a snare, claptrap, cant, mere words, lame and impotent conclusion, meshes of sophistry, cobwebs of sophistry, flaw in an argument, weak point, bad case, overrefinement, hairsplitting, intuitive, instinctive, impulsive, independent of reason, anterior to reason, gratuitous, hazarded, unconnected, unreasonable, illogical, false, unsound, invalid, unwarranted, not following, inconsequent, inconsequential, inconsistent, absonous, absonant, unscientific, untenable, inconclusive, incorrect, fallacious, fallible, groundless, unproved, non sequitur, it does not follow, deceptive, sophistical, jesuitical, illusive, illusory, specious, hollow, plausible, ad captandum, evasive, irrelevant, weak, feeble, poor, flimsy, loose, vague, irrational, nonsensical, foolish, frivolous, pettifogging, quibbling, finespun, overrefined, at the end of one's tether, au bout de son latin, intuitively, by intuition, illogically, non constat, that goes for nothing.Error
N error, fallacy, misconception, misapprehension, misstanding, misunderstanding, inexactness, laxity, misconstruction, miscomputation, non sequitur, mis-statement, mis-report, mumpsimus, mistake, miss, fault, blunder, quiproquo, cross purposes, oversight, misprint, erratum, corrigendum, slip, blot, flaw, loose thread, trip, stumble, botchery, slip of the tongue, slip of the lip, Freudian slip, slip of the pen, lapsus linguae, clerical error, bull, haplography, illusion, delusion, snare, false impression, false idea, bubble, self-decit, self-deception, mists of error, heresy, hallucination, false light, dream, fable, bias, misleading, erroneous, untrue, false, devoid of truth, fallacious, apocryphal, unreal, ungrounded, groundless, unsubstantial, heretical, unsound, illogical, inexact, unexact inaccurate, incorrect, indefinite, illusive, illusory, delusive, mock, ideal, spurious, deceitful, perverted, controvertible, unsustainable, unauthenticated, untrustworthy, exploded, refuted, discarded, in error, under an error, mistaken, tripping, out, out in one's reckoning, aberrant, beside the mark, wide of the mark, wide of the truth, way off, far off, astray, on a false scent, on the wrong scent, in the wrong box, outside the ballpark, at cross purposes, all in the wrong, all out, more or less, errare est humanum, mentis gratissimus error, on the dubious waves of error tost, to err is human, to forgive divine, you lie -- under a mistake.For further exploring for "groundless" in Webster Dictionary Online