I. hy ‧ drate 1 /ˈhaɪdreɪt/ BrE AmE verb [transitive usually passive]
to supply someone or something with water to keep them healthy and in good condition OPP dehydrate :
After you run, drink plenty of water to stay well hydrated.
—hydration /haɪˈdreɪʃ ə n/ noun [uncountable]
II. hydrate 2 BrE AmE noun [countable] technical
[ Date: 1800-1900 ; Origin: hydro- ]
a chemical substance that contains water