Definition of oyabun in English:

oyabun

Pronunciation /ˈɔɪəbʊn/ /ˈəʊjəbʊn/

noun

  • In Japan: a boss, a chief; specifically the boss of an organized crime syndicate or of a labour organization.

Origin

1940s; earliest use found in American Political Science Review. From Japanese oyabun boss, head from oya parent + -bun, suffix denoting an assumed relation between one person and another, or the person thus related (from Middle Chinese).