noun - Hydration is a substance that contains water and is used to restore or maintain fluid balance during an open water swim. The importance of hydration to prevent dehydration during an open water swim cannot be overemphasized.
Water, juices, teas, Gatorade, flat Coca-Cola or Mountain Dew, fortified water drinks, and other commercial or customized liquids help to restore or maintain fluid balance.
1795–1805; HYDR + -ATE
Some nutritionists argue that drinks that include caffeine do not hydrate because it is also a diuretic.