arcana

uncountable

Specialized knowledge that is mysterious to the uninitiated.

Japanese Meaning

限られた者だけが知る、秘密で神秘的な専門知識

The old librarian guarded the arcana of the manuscript, revealing them only to trusted scholars.

年老いた司書はその写本の秘伝の知識を守り、信頼できる学者にだけそれを明かした。

Sense（1）

Specialized knowledge that is mysterious to the uninitiated.

Thou deign'st no answer,—or I fain would ask

If since thy bright creation, thou hast seen

Ought like a Newton, whose admitted eye

The arcana of the universe explored

Light's subtle ray its mechanism disclosed,

The impetuous comet his mysterious lore

Unfolded,