THESAURUS
Vacuous
airy, asinine, awkward, bare, barren, bland, blank, blankminded, bleached, callow, calm, catchpenny, characterless, clear, devoid, dumb, empty, empty-headed, empty-minded, empty-pated, empty-skulled, existless, fatuous, featureless, flimsy, foolish, fribble, fribbling, frivolous, frothy, futile, gauche, green, groping, hollow, idle, ignorant, inane, incogitant, inexperienced, innocent, insipid, jejune, know-nothing, lacking, light, minus, missing, naive, negative, nescient, nirvanic, nonexistent, nugacious, nugatory, null, null and void, oblivious, otiose, passive, quietistic, rattlebrained, rattleheaded, raw, relaxed, scatterbrained, shallow, silly, simple, slender, slight, strange to, superficial, tentative, thoughtfree, thoughtless, tranquil, trifling, trite, trivial, unacquainted, unapprized, uncomprehending, unconversant, unenlightened, unexisting, unfamiliar, unideaed, unilluminated, uninformed, uninitiated, unintellectual, unintelligent, unknowing, unoccupied, unposted, unreasoning, unrelieved, unripe, unsure, unthinking, unversed, vacant, vain, vapid, void, white, windy, with nothing inside, without being, without content
ROGET THESAURUS
Vacuous
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.
Absence
N
absence, inexistence, nonresidence, absenteeism, nonattendance, alibi, emptiness, void, vacuum, vacuity, vacancy, tabula rasa, exemption, hiatus, lipotype, truant, absentee, nobody, nobody present, nobody on earth, not a soul, ame qui vive, absent, not present, away, nonresident, gone, from home, missing, lost, wanting, omitted, nowhere to be found, inexistence, empty, void, vacant, vacuous, untenanted, unoccupied, uninhabited, tenantless, barren, sterile, desert, deserted, devoid, uninhabitable, without, minus, nowhere, elsewhere, neither here nor there, in default of, sans, behind one's back, the bird has flown, non est inventus, absence makes the heart grow fonder, absent in body but present in spirit, absento nemo ne nocuisse velit, Achilles absent was Achilles still, aux absents les os, briller par son absence, conspicuous by his absence, in the hope to meet shortly again and make our abs.
Incogitancy
N
incogitancy, vacancy, inunderstanding, fatuity thoughtlessness, vacuity, couch potato, vegetable, vacant, unintellectual, unideal, unoccupied, unthinking, inconsiderate, thoughtless, mindless, no-brain, vacuous, absent, diverted, irrational narrow-minded, unthought of, undreamt 'of, unconsidered, off one's mind, incogitable, not to be thought of, absence d'esprit, pabulum pictura pascit inani.