1.  inadequacy(n = noun.attribute) deficiency, insufficiency - lack of an adequate quantity or number; "the inadequacy of unemployment benefits"
is a kind of amount
has particulars: exiguity, leanness, meagerness, meagreness, poorness, scantiness, scantness, deficit, shortage, shortfall, scarceness, scarcity, slenderness
Antonym: adequacy

2.  inadequacy(n = noun.state) insufficiency - a lack of competence; "pointed out the insufficiencies in my report"; "juvenile offenses often reflect an inadequacy in the parents"
is a kind of failing, weakness

3.  inadequacy(n = noun.attribute) inadequateness - unsatisfactoriness by virtue of being inadequate;
is a kind of unsatisfactoriness
Antonym: adequacy

   The quality or state of being inadequate or insufficient; defectiveness; insufficiency; inadequateness. [1913 Webster]
"The inadequacy and consequent inefficacy of the alleged causes." [1913 Webster]

N  insufficiency, inadequacy, inadequateness, incompetence, deficiency, imperfection, shortcoming, paucity, stint, scantiness, none to spare, bare subsistence, scarcity, dearth, want, need, lack, poverty, exigency, inanition, starvation, famine, drought, dole, mite, pittance, short allowance, short commons, half rations, banyan day, emptiness, poorness, depletion, vacancy, flaccidity, ebb tide, low water, a beggarly account of empty boxes, indigence, insolvency, drain of resources, impoverish, stint, put on short allowance, do insufficiently, scotch the snake, Adj, insufficient, inadequate, too little, not enough, unequal to, incompetent, weighed in the balance and found wanting, perfunctory, deficient, wanting imperfect, ill-furnished, ill-provided, ill- stored, ill-off, slack, at a low ebb, empty, vacant, bare, short of, out of, destitute of, devoid of, bereft of, denuded of, dry, drained, unprovided, unsupplied, unfurnished, unreplenished, unfed, unstored, untreasured, empty-handed, meager, poor, thin, scrimp, sparing, spare, stinted, starved, starving, halfstarved, famine-stricken, famished, jejune, scant, scarce, not to be had, not to be had for love or money, not to be had at any price, scurvy, stingy, at the end of one's tether, without resources, in want, in debt, insufficiently, in default of, for want of, failing, semper avarus eget.

N  inutility, uselessness, inefficacy, futility, ineptitude, inaptitude, unsubservience, inadequacy, inefficiency, unskillfulness, disservice, unfruitfulness (unproductiveness), labor in vain, labor lost, labor of Sisyphus, lost trouble, lost labor, work of Penelope, sleeveless errand, wild goose chase, mere farce, tautology, supererogation, vanitas vanitatum, vanity, inanity, worthlessness, nugacity, triviality, caput mortuum, waste paper, dead letter, blunt tool, litter, rubbish, junk, lumber, odds and ends, cast-off clothes, button top, shoddy, rags, orts, trash, refuse, sweepings, scourings, offscourings, waste, rubble, debris, detritus, stubble, leavings, broken meat, dregs, weeds, tares, rubbish heap, dust hole, rudera, deads, fruges consumere natus, useless, inutile, inefficacious, futile, unavailing, bootless, inoperative, inadequate, inservient, unsubservient, inept, inefficient, of no avail, ineffectual, incompetent, stale, flat and unprofitable, superfluous, dispensable, thrown away, abortive, worthless, valueless, priceless, unsalable, not worth a straw, dear at any price, vain, empty, inane, gainless, profitless, fruitless, unserviceable, unprofitable, ill-spent, unproductive, hors de combat, effete, past work, obsolete, fit for the dust hole, good for nothing, of no earthly use, not worth having, not worth powder and shot, leading to no end, uncalled for, unnecessary, unneeded, uselessly, to little purpose, to no purpose, to little or no purpose, Int, cui bono?, what's the good!, actum ne agas, chercher une aiguille dans une botte de foin, tanto buon che val niente.

N  imperfection, imperfectness, deficiency, inadequacy, peccancy, immaturity, fault, defect, weak point, screw loose, flaw, gap, twist, taint, attainder, bar sinister, hole in one's coat, blemish, weakness, half blood, shortcoming, drawback, seamy side, mediocrity, no great shakes, no great catch, not much to boast of, one-horse shay, imperfect, not perfect, deficient, defective, faulty, unsound, tainted, out of order, out of tune, cracked, leaky, sprung, warped, lame, injured, peccant, frail, inadequate, crude, incomplete, found wanting, below par, short-handed, below its full strength, under its full strength, below its full complement, indifferent, middling, ordinary, mediocre, average, so-so, coucicouci, milk and water, tolerable, fair, passable, pretty well, pretty good, rather good, moderately good, good, good enough, well enough, adequate, decent, not bad, not amiss, inobjectionable, unobjectionable, admissible, bearable, only better than nothing, secondary, inferior, second-rate, second-best, one-horse, almost, to a limited extent, rather, pretty, moderately, passing, only, considering, all things considered, enough, surgit amari aliquid.