objects whole behavior/value can't be changed at runtime, once set
A freezable object has two states – frozen and unfrozen. When an object is frozen, it cannot be modified and it cannot even fires events but the unfrozen state, it works same as a normal object.
A Freezable object is those objects which is unchangeable. The freezable objects are better and safer to shared between the threads.
Official link: http://msdn.microsoft.com/en-us/library/ms750509(v=vs.110).aspx
http://www.c-sharpcorner.com/Blogs/1127/
A Freezable object is a special type of object that exists in two states:frozen and unfrozen. In unfrozen state,the Freezable object appears as if it is simple object.But in frozen state, the Freezable object can not be modified.