secret techniques; esoteric knowledge; mysteries
Refers to the deepest, most closely guarded secrets of an art, craft, or martial tradition. Often used in contexts like 奥義秘伝を伝授する (to impart the secret teachings).
The secret techniques of that school have been passed down from father to son.
He was initiated into the esoteric knowledge by his master.
Compound of 奥義 (inner mysteries, profound principles) and 秘伝 (secret transmission). The exact historical derivation is uncertain, but the term is conventionally associated with esoteric teachings in traditional Japanese arts and martial arts.