hydrate
n.
1802, "compound of water and another chemical," from French hydrate, coined c.1800 by French chemist Joseph-Louis Proust (1754-1826) from Greek hydr-, stem of hydor "water" (see water, n.1).
v.
1850, "to form a hydrate;" 1947 as "to restore moisture;" from Greek hydr-, stem of hydor "water" (see water, n.1) + -ate(2). Related: Hydrated; hydrating.