› ECONOMICS, POLITICS, FINANCE to become or make something or someone become less powerful, successful, effective, etc.: A series of scandals weakened investor confidence. The plan has divided the country and weakened the government. They will reduce interest rates if the economy weakens. They slashed profit growth forecasts yesterday in the face of poor sales and weakening consumer spending.
› STOCK MARKET, FINANCE if markets, investments, etc. weaken, or if something weakens them, they fall in value: weaken against sth Sterling might weaken against the euro if the dollar does. The shares weakened 2.5p to 225.25p. German producer prices weakened in July.