A homeboy is a friend, especially a male friend, from the same place as you — the same street, the same neighbourhood, sometimes the same group or gang. Young people say it. It began as African-American city slang in the twentieth century, from hometown plus boy: a boy from home. Today you hear it most from African-Americans and Latinos in the United States, in rap, in films, and in street talk. It can be warm: your homeboy is your guy, someone who stands with you. It can sit closer to gang talk too, a man from your set. People also toss it out as a greeting, like “Hey, homeboy,” the way someone might say bro. It is informal. You would not put it in a careful school essay unless you were quoting. Learners outside the US often pick it up from music and movies; said by someone who is not part of that world, it can sound like copying. It does not mean a boy who stays at home.