Definition of weak :
1. Deficient in strength of body; feeble; infirm; sickly; debilitated; enfeebled; exhausted.
2. Feeble of mind; wanting discernment; lacking vigor; spiritless; as, a weak king or magistrate.
3. Lacking ability for an appropriate function or office; as, weak eyes; a weak stomach; a weak magistrate; a weak regiment, or army.
4. Lacking contrast; as, a weak negative.
5. Lacking force of utterance or sound; not sonorous; low; small; feeble; faint.
6. Lacking in elements of political strength; not wielding or having authority or energy; deficient in the resources that are essential to a ruler or nation; as, a weak monarch; a weak government or state.
7. Lacking in good cards; deficient as to number or strength; as, a hand weak in trumps.
8. Not able to resist external force or onset; easily subdued or overcome; as, a weak barrier; as, a weak fortress.
9. Not able to sustain a great weight, pressure, or strain; as, a weak timber; a weak rope.
10. Not able to withstand temptation, urgency, persuasion, etc.; easily impressed, moved, or overcome; accessible; vulnerable; as, weak resolutions; weak virtue.
11. Not firmly united or adhesive; easily broken or separated into pieces; not compact; as, a weak ship.
12. Not having full confidence or conviction; not decided or confirmed; vacillating; wavering.
13. Not having power to convince; not supported by force of reason or truth; unsustained; as, a weak argument or case.
14. Not possessing or manifesting intellectual, logical, moral, or political strength, vigor, etc.
15. Not prevalent or effective, or not felt to be prevalent; not potent; feeble.
16. Not stiff; pliant; frail; soft; as, the weak stalk of a plant.
17. Not thoroughly or abundantly impregnated with the usual or required ingredients, or with stimulating and nourishing substances; of less than the usual strength; as, weak tea, broth, or liquor; a weak decoction or solution; a weak dose of medicine.
18. Pertaining to, or designating, a noun in Anglo- Saxon, etc., the stem of which ends in - n. See Strong, 19 ( b).
19. Pertaining to, or designating, a verb which forms its preterit ( imperfect) by a variation in the root vowel, and the past participle ( usually) by the addition of - en ( with or without a change of the root vowel); as in the verbs strive, strove, striven; break, broke, broken; drink, drank, drunk. Opposed to weak, or regular. See Weak.
20. Resulting from, or indicating, lack of judgment, discernment, or firmness; unwise; hence, foolish.
21. Tending toward a lower price or lower prices; as, wheat is weak; a weak market.
22. Tending towards lower prices; as, a weak market.
23. To make or become weak; to weaken.
24. Wanting in point or vigor of expression; as, a weak sentence; a weak style.
25. Wanting in power to influence or bind; as, weak ties; a weak sense of honor of duty.
26. Wanting physical strength.
sluttish, strong, blurred, breakaway, milk-and-water, pitiful, precarious, anaemic, light-headed, sleazy, enfeebled, tottery, effete, bad, off-screen, imperative, wet, slack, antigrowth, federal, characterless, terrible, atonic, inaudible, light-colored, unreasoning, lightsome, unsteady, good-looking, unreasonable, inconspicuous, healthy, rotten, weakling, wispy, invisible, affective, incomplete, weak-willed, expert, deflationary, collectivist, effervescent, easy, derelict, debut, dilute, delicate, assailable, sick, ramshackle, invertebrate, low-grade, senile, shoddy, unaccented, carbonated, absolute, trained, nerveless, poor, restricted, buoyant, idle, continuous, washy, future, untrained, full-face, directionless, alveolar, fallacious, faded, handsome, flooded, casual, dry, fainthearted, rachitic, inconsequent, down-and-out, exclusive, likely, friable, capitalist, unsound, imperfect, handcuffed, weakened, unorganized, prostrated, half-hearted, timid, ineffectual, alcoholic, inconceivable, metaphysical, deep, low-powered, finite, interpretive, slight, worn, within limits, fallible, consonant, theoretical, makeshift, helpless, conceptual, burning, clean, implausible, wishy-washy, under control, deterministic, central, regular, susceptible, paltry, all-star, insubstantial, nonrational, close vowel, unconceivable, blind, aggregate, calorie-free, faltering, vulnerable, insecure, backward, economic, ineffective, tumbledown, acutely, aspiration, evergreen, ill-defined, overwhelmed, autonomous, high and dry, embarrassing, assonance, chiseled, tender, bleached, thinned, orthodox, prostrate, illegitimate, interpretative, clear, incredible, namby-pamby, delicately balanced, asthenic, wimpish, creaky, be easily led, washed-out, crumbly, ability, brave, improbable, bilabial, watered-down, languid, bitter, craggy, governing, low-cal, limited, experienced, worn down, tenuous, indistinct, utopian, gutless, basic, hamstrung, loose, prohibitive, shadowy, dire, depth, lame, small, faint-hearted, unclouded, drinkable, specific, absolutist, unstressed, impuissant, deep-seated, handicapped, full-bodied, decaffeinated, irrational, corked, disgraceful, furrowed, invalid, lame-duck, exposed, thin, wonky, lite, young, dim, swooning, nonconformist, engulfed, courageous, debile, black, governmental, bullish, enervated, waterish, immature, forceless, low, limiting, crap, muffled, wearied, vague, dull, overpowered, incapacitated, fresh, flea-bitten, weak-kneed, weakly, effeminate, loud, change, bicameral, paralyzed, woebegone, sapped, sapless, unstrung, nervous, hog-tied, jerry-built, inconsequential, pale, unstable, palsied, weak-minded, inundated, causative, raw, green, colonialist, overcome, wan, unconvincing, impersonal, tottering, whispered, unforceful, short, democratic, baby-faced, lax, guest, tripping, wobbly, shaky, bankable, purposeless, closed syllable, wimpy, fresh-faced, flabby, hatchet-faced, popular, aspirate, economically, unbelievable, live, diluted, second-rate, promiscuous, restrictive, abstemious, scant, imperceptible, wakeful, wanton, reeking, unsubstantial, puny, fine, pallid, limp-wristed, fuzzy, abstract, active, light, lightheaded, intransitive, undisciplined, breakable, swamped, softened, brittle, malnourished, affricate, ergative, subtle, human, adynamic
impotent (part of speech: adjective)
irresolute (part of speech: adjective)
impulsive, undependable, fly-by-night, changeable, shrinking, ambivalent, inconsistent, uncertain, unresolved, indecisive, tentative, unwilling, irresponsible, insipid, shy, erratic, irresolute, shifty, yellow, unsure, capricious, hesitant, dillydallying, shilly-shally, undecided, volatile, flitting, double-minded, watery, vacillating, halfhearted, spineless, fickle
feeble (part of speech: adjective)
tasteless (part of speech: adjective)
weary (part of speech: adjective)
fatigued, toilsome, over-weary, footsore, apathetic, sleepy, limp, flaccid, droopy, depressed, wayworn, uphill, tired, worn-out, bored, drowsy, frazzled, exhausted, trying, weary, wasted, cheerless, blue, listless
weak (part of speech: adjective)