"Oyabun" is a Japanese word used to refer to a leader or boss, especially in the context of organized crime or a gang. There are several synonyms for this word that may be used interchangeably, depending on the situation and context. Some of the common synonyms for "oyabun" include "kumicho," "godfather," "boss," "capo," "chieftain," and "padrone," among others. These words generally connote a person with power and authority, who is in charge of a group or organization. The specific connotations of each word may differ slightly, but they share the same meaning as "oyabun" and are often used in similar contexts.