Answer: freezing
Step-by-step explanation:
In matter, freezing is one of the physical change of state. Others include; sublimation, vaporization, condensation, and melting. All matter can exist in either solids, liquids or gases, yet matter can be transformed from one to another(that is from solid to liquid, liquid to solid, solid to gas , liquid to gas and so on).
Water naturally occur in liquid state, but it can be transformed from one phase to another. When water in its liquid form is changed/transformed into its solid phase(known as ice) , we term this physical change of matter as FREEZING. Freezing is done by lowering the temperature of water. We can reverse freezing of water back by just increasing the temperature of the solid water(ice), and this is known as Defreezing or MELTING.