The phrase "be in the possession of" implies ownership or control over something. There are several synonyms that can be used to convey the same meaning, such as "have," "hold," "own," "possess," "control," "dominate," "govern," and "command." Depending on the context, each of these words can be used to convey a slightly different nuance. For example, "own" implies a legal or formal ownership, while "possess" connotes a more temporary or casual control over something. Similarly, "control" implies a greater level of authority or power over something, while "hold" suggests a more physical or tangible grasp on it. Regardless of the specific word used, they all convey a sense of possessing something.