innermost secrets of a discipline; esoteric teachings
Refers to the deepest, most advanced teachings in traditional Japanese arts (e.g., tea ceremony, martial arts, flower arrangement), often transmitted orally and only to select disciples. The cross-reference to 伝 (sense 3) suggests a connection to the concept of 'tradition' or 'transmission' of secret knowledge.
See also: 伝 (でん)
Long training is required before one is permitted to learn the innermost secrets of the tea ceremony.
He received the esoteric teachings from his master.
Compound of 奥 (oku, 'inner part') and 伝 (den, 'transmission'). The term likely originated in the context of traditional Japanese arts where knowledge was passed down orally and in stages, with the deepest secrets reserved for advanced practitioners.