weak / wēk/ • adj. 1. lacking the power to perform physically demanding tasks; lacking physical strength and energy: she was recovering from the flu and was very weak. ∎  lacking political or social power or influence: the central government had grown too weak to impose order | [as pl. n.] (the weak) the new king used his powers to protect the weak. ∎  (of a crew, team, or army) containing too few members or members of insufficient quality. ∎  (of a faculty or part of the body) not able to fulfill its functions properly: he had a weak stomach. ∎  of a low standard; performing or performed badly: the choruses on this recording are weak. ∎  not convincing or logically forceful: the argument is an extremely weak one a weak plot. ∎  exerting only a small force: a weak magnetic field.2. liable to break or give way under pressure; easily damaged: the salamander's tail may be broken off at a weak spot near the base. ∎  lacking the force of character to hold to one's own decisions, beliefs, or principles; irresolute. ∎  (of a belief, emotion, or attitude) not held or felt with such conviction or intensity as to prevent its being abandoned or dispelled: their commitment to the project is weak. ∎  not in a secure financial position: people have no faith in weak banks. ∎  (of prices or a market) having a downward tendency.3. lacking intensity or brightness: a weak light from a single street lamp. ∎  (of a liquid or solution) lacking flavor or effectiveness because of being heavily diluted: a cup of weak coffee. ∎  displaying or characterized by a lack of enthusiasm or energy: she managed a weak, nervous smile. ∎  (of features) not striking or strongly marked: his beard covered a weak chin. ∎  (of a syllable) unstressed.4. Gram. denoting a class of verbs in Germanic languages that form the past tense and past participle by addition of a suffix (in English, typically -ed); contrasted with strong.5. Physics of, relating to, or denoting the weakest of the known kinds of force between particles, which acts only at distances less than about 10⁻¹⁵ cm, is very much weaker than the electromagnetic and the strong interactions, and conserves neither strangeness, parity, nor isospin.PHRASES: the weaker sex [treated as sing. or pl.] dated, derog. women regarded collectively.weak in the knees helpless with emotion.the weak link the point at which a system, sequence, or organization is most vulnerable; the least dependable element or member.DERIVATIVES: weak·ish adj.ORIGIN: Old English wāc ‘pliant,’ ‘of little worth,’ ‘not steadfast,’ reinforced in Middle English by Old Norse veikr, from a Germanic base meaning ‘yield, give way.’