roar·ing / ˈrôring/ • adj. 1. (of a person, crowd, or animal) making a loud and deep sound, esp. as an expression of pain, anger, or approval: he was greeted everywhere with roaring crowds. ∎ (of something inanimate, esp. a natural phenomenon) making a loud, deep, or harsh prolonged sound: a swollen, roaring river. ∎ (of a fire) burning fiercely and noisily. ∎ (of a period of time) characterized by optimism, buoyancy, or excitement: the roaring twenties. ∎ (of business) lively; brisk: cafes that do a roaring trade. ∎ chiefly archaic behaving or living in a noisy riotous manner.2. inf. obviously or unequivocally the thing mentioned (used for emphasis): the final week of Hamlet was a roaring success | two roaring drunk firemen. DERIVATIVES: roar·ing·ly adv.