The word "braker" is quite uncommon and a synonym for it is not easily available. However, depending on the context, there are several possible alternatives. For example, if we are referring to a person who is slowing down something or someone, we can use the word "decelerator." If we are talking about a machine or device that performs this action, "slowing mechanism" or "dampening device" could work. In a sports context, "defender" or "blocker" could also be used. It is essential to choose the right synonym depending on the specific context to convey the intended meaning effectively.