Definition of water Plasticization
Quoting Wikipedia,


  Plasticizers (UK: plasticisers) or dispersants are additives that increase the plasticity or decrease the viscosity of a material.


As far as most research papers say, water is not plasticized, but rather it acts as a plasticizing agent for other substances such as starch films as mentioned in this article. Water makes these films permanently deformed upon external stress and resists reverting back to its original shape.