Let us understand all the terms
Hydration : this is the addition of water to anything. It can be addition of water to double or triple bond, absorption of water by a substance. so it cannot be loss of water.
Deliquescent : it is the absorption of water by a substance and getting dissolved in it. Like NaOH is a deliquescent substance.
Solvation: It is the phenomenon where a substance get surrounded by solvent molecules. If solvent is water it is known as hydration.
Thus the answer is
effloresce : where a substance loses water.