i ‧ so ‧ ton ‧ ic drink /ˌaɪsətɒnɪk ˈdrɪŋk $ -tɑː-/ BrE AmE noun [countable]
a drink made especially for people who are exercising or playing sport, containing ↑ electrolyte s which help your body take in liquid effectively, and ↑ carbohydrate s that give your body extra energy