Synonyms for Inadequate:

adj.

bad (adjective)
defective, inferior, detrimental, vile, arrant, bad, inadvisable, faulty, invalid, irremediable, unpleasant, wrong, unfavorable, wretched, unsound, displeasing, black, baneful, ill-suited, poor, unsatisfactory.
defective, insufficient, incompetent (adjective)
feeble, inappreciable, niggardly, lacking, incompetent, inconsiderable, faulty, failing, poor, meager, bare, deficient, depleted, thin, spare, short, shy, small, parsimonious, unproductive, dry, impotent, imperfect, incomplete, low, lame, skimpy, weak, miserly, incapable, sterile, sparse, scarce, scanty, barren, unqualified.
deficient (adjective)
lacking, imperfect, wanting, deficient, insufficient.
exiguous (adjective)
meager.
feeble (adjective)
helpless.
imperfect (adjective)
deficient, faulty, spoiled, blotched, tainted, defective, second-rate, incomplete, blemished, flawed, imperfect.
impotent (adjective)
disabled, feeble, incapable, impotent, powerless, weak, incompetent, sterile.
incomplete (adjective)
incomplete.
insufficient (adjective)
scarce, meager, scanty, skimpy, sparse, stingy, miserly, Flyspeck, niggardly, insufficient.
short (adjective)
short, niggardly.
unacceptable (adjective)
untenable, inappropriate, unsuitable, deficient, inferior, insufficient, intolerable, unsatisfactory, unacceptable, inadmissible.
useless (adjective)
good-for-nothing, detrimental, fruitless, impractical, unserviceable, futile, ineffectual, nonfunctional, useless, ineffective, unsuitable, unusable, unworkable.

n.

awful, someone couldn't do something if they tried, inexpert, no-good, amateur. unfit, ability, unqualified. inadequate (noun)
incompetent, understaffed, deficient, insufficient, short, incapable, unequal to, poor, undermanned, lacking, wanting, short-handed, short-staffed.
incompetent (noun)
ineffectual, inept.

Other synonyms:

derisory, lame, sorry, small, unqualified, amateur. shy, bare, under. helpless, ineffectual. tight. scanty
exiguous, spare.
sparse
thin.
unsuitable
unfit.

Usage examples for inadequate

  1. Two days of inadequate food and such ideas came! – Operation Terror by William Fitzgerald Jenkins
  2. All the wars of primitive man were inadequate – A Breath of Prairie and other stories by Will Lillibridge
  3. Ordinary language is inadequate to express all that was achieved, seen, and felt. – Over the Top With the Third Australian Division by G. P. Cuttriss