Synonyms of weak

1 Syllable: slight, scant, paled, limp, frail, dim, meek, bland, faint, shrimp, mild, spent, dims, sick, slack
2 Syllables: brittler, gorked, spastic, sicker, subpar, numbskull, pigeon, groggy, cornball, pallid, meekest, laid-low, sickish, fainter, feebler, slighter, uncool, loopy, flimsier, blandest, ho-hum, doughier, beat-up, slightest, doughy, sickly, rootless, palsied, stale, tomfool, crispy, dimmest, ailing, rotten, palest, feeblest, naysaying, scrapper, coner, torpid, slender, timid, ungrown, brittlest, shrimper, hohum, dimmer, crispier, junker, matest, zestless, painless, wearied, stenchy, flaccid, run-down, languid, sickest, wornout, flimsy, laid-up, ghastlier, haggard, shaky, sluggish, spindly, weakly, meeker, pithless, faultier, blander, wobbly, rocky, ghastly, milder, strengthless, punier, puny, unsound, prosy, wretched, mildest, meager, feckless, faintest, bummed, soaper, paler, nervous, dotard, prosier, shakiest, snoozy, tender, reachy, foolish, unwell, scrimpy, vapid, shakier, half-pint, faulty, gutless, wasted, mater, flagging, maudlin, feeble, sapless, dumdum, helpless, slusher, infirm
3 Syllables: weariful, retardo, insipid, aquake, ashake, tottery, makeshift, arthritic, unshielded, frangible, tottering, unbacked, tremorous, dissentient, sclerotic, gracile, rachitic, dogeared, innocuous, decrepit, untended, unhealthy, dog-eared, untrusty, powerless, cowardly, careworn, inanest, unsure, prostrate, atonic, rheumatic, vincible, fallible, fragile, basket-case, inane, hesitant, pregnable, supine, tenderer, waterish, unguarded, unable, unstable, impotent, softheaded, doddering, rickety, senile, puerile, forceless, languorous, effete, faint-hearted, bone-weary, useless, tuckered, sleepyhead, indistinct, senescent, cowhearted, demulcent, tasteless, anemic, jellyfish, lymphatic, watery, niggardly, deficient, exhausted, weak-willed, diluted, butterflies, spineless, unsteady, wavering, subnormal, retarded, weakened, breakable, impuissant, creatural, uncertain, bipedal, fainthearted
4 Syllables: implausible, unconvincing, scaredy-cat, unreliable, jellylike, unusable, delicate, neurasthenic, unsubstantial, down-at-the-heel, assailable, uncared-for, meanspirited, shatterable, fracturable, attackable, sublunary, milk-and-water, on-the-fence, unfunctional, unusuable, inproficient, unequipped, negative, out-of-action, improficient, vulnerable, improbable, babylike, nonfunctional, longanimous, chicken-hearted, inutile, unprotected, lenitive, defenseless, imbecilic, unresisting, infantine, privative, insubstantial, wishy-washy, characterless, enervated, ineffectual, watered-down, incapable, sidelined, mean-spirited, inefficient, yellow-bellied, uncircumspect
5 Syllables: underachieving, unworkmanlike, undefendable, lackadaisical, unpleasurable, insupposable, unstimulating, hundred-to-one, unretentive, inconceivable, unbelievable, apprehensive, hospitalized, amoebalike, undependable, inadequate, unconceivable, irresolute, debilitated
6 Syllables: unaffirmative, unsatisfactory, incapacitated