J9, J09, J 9 or J-9 may refer to:
== Military == Chengdu J-9, a designation assigned to a 1975 Chinese interceptor aircraft that never progressed beyond initial studies , a 1940 British Royal Navy Junkers J 9, a factory designation for the 1917 German Junkers D.I fighter aircraft Seversky J9, a Swedish WW2 fighter plane
Discovered by embedding cosine similarity (sentence-transformers MiniLM, 384-dim).