i·so·ton·ic drink /ˌaɪsətɒnɪk ˈdrɪŋk $ -tɑː-/ noun [countableC] a drink made especially for people who are exercising or playing sport, containing electrolytes which help your body take in liquid effectively, and carbohydrates that give your body extra energy 等渗饮料〔含电解液和碳水化合物〕