The phrase "new boy" is often used to refer to someone who is new to a specific community or group. However, there are many different synonyms that can be used to describe a new boy. One option is to use the phrase "newcomer," which has the same connotation but is a bit more formal. Alternatively, "freshman" can be used to describe a new boy in a school setting. "Novice" is another possible synonym, which emphasizes a lack of experience or knowledge in a particular field. Other phrases that could be used include "newbie," "rookie," and "greenhorn." Ultimately, the choice of synonym depends on the context and tone desired.