not strong; liable to yield, break, or collapse under pressure or strain; fragile; frail

a weak fortress; a weak spot in armor.

lacking in bodily strength or healthy vigor, as from age or sickness; feeble; infirm

a weak old man; weak eyes.

not having much political strength, governing power, or authority

a weak nation; a weak ruler.

lacking in force, potency, or efficacy; impotent, ineffectual, or inadequate

weak sunlight; a weak wind.

lacking in rhetorical or creative force or effectiveness

a weak reply to the charges; one of the author's weakest novels.

lacking in logical or legal force or soundness

a weak argument.

deficient in mental power, intelligence, or judgment

a weak mind.

not having much moral strength or firmness, resolution, or force of character

to prove weak under temptation; weak compliance.

deficient in amount, volume, loudness, intensity, etc.; faint; slight

a weak current of electricity; a weak pulse.

deficient, lacking, or poor in something specified

a hand weak in trumps; I'm weak in spelling.

deficient in the essential or usual properties or ingredients

weak tea.

unstressed, as a syllable, vowel, or word.

(of Germanic verbs) inflected with suffixes, without inherited change of the root vowel, as English work, worked, or having a preterit ending in a dental, as English bring, brought.

(of Germanic nouns and adjectives) inflected with endings originally appropriate to stems terminating in -n, as the adjective alte in German der alte Mann (the old man).

(of wheat or flour) having a low gluten content or having a poor quality of gluten.

Photography . thin; not dense.

Commerce . characterized by a decline in prices

The market was weak in the morning but rallied in the afternoon.

adjective

firm , potent , strong , bold , brave , confident , loud , noisy , able , capable , fit , sufficient , guarded , protected , safe , secure , concentrated , thick

adjective

anemic , debilitated , decrepit , delicate , effete , enervated , exhausted , faint , feeble , flaccid , flimsy , forceless , fragile , frail , hesitant , impuissant , infirm , insubstantial , irresolute , lackadaisical * , languid , languorous , limp , makeshift , out of gas , powerless , prostrate , puny , rickety , rocky * , rotten , senile , shaky , sickly , sluggish , spent , spindly , supine , tender , torpid , uncertain , undependable , unsound , unsteady , unsubstantial , wasted , wavering , weakened , weakly , wobbly , faint-hearted , fluctuant , frightened , impotent , indecisive , ineffectual , insecure , laid-back * , nerveless , nervous , palsied , soft , spineless , timorous , unreliable , unstable , unsure , vacillating , weak-kneed , wimpy , wishy-washy * , zero * , bated , dim , distant , dull , gentle , imperceptible , inaudible , indistinct , low , muffled , pale , poor , quiet , reedy , slight , small , stifled , thin , unaccented , unstressed , whispered , faulty , flabby , green * , handicapped , hollow , immature , implausible , improbable , inadequate , incompetent , incomplete , inconceivable , inconclusive , incredible , ineffective , inept , invalid , lacking , lame , limited , pathetic , raw , shallow , slim , substandard , thick , unbelievable , unconvincing , unprepared , unqualified , unsatisfactory , untrained , wanting , accessible , assailable , defenseless , helpless , indefensible , unguarded , unprotected , unsafe , untenable , wide-open * , woundable , dilute , diluted , insipid , milk-and-water , runny , tasteless , washy , waterish , watery , precarious , tottering , tottery , incapable , watered-down , unconceivable , anile , anodyne , asthenic , atonic , attenuated , bland , brittle , cowardly , debilitating , defective , degenerate , devitalized , devitalizing , dissolute , effeminate , emasculated , enervating , enfeebled , errable , erring , etiolated , exposed , fallible , feckless , gauzy , illogical , indiscreet , inefficacious , invertebrate , lethargic , lily-livered , peccable , pliable , pliant , pregnable , sleazy , tenuous , unsustained , valetudinarian , vapid , vulnerable , weakening , wishy-washy , worn , young