arcana

Arcana is the plural form of arcanum, a Latin word meaning secret or mystery. In general usage, arcana refers to things that are hidden or esoteric, knowledge accessible to a restricted group, often associated with mysticism, occult traditions, or specialized fields.

In classical and medieval contexts, writers spoke of the arcana of nature or of theology—the hidden truths behind appearances. The term is common in discussions of alchemy, magic, and speculative philosophy, where arcana designate guarded knowledge or powers.

In cards: The Tarot divides into Major Arcana and Minor Arcana. The Major Arcana comprises 22 trump-like cards that depict archetypal themes and life stages; the Minor Arcana has 56 cards in four suits, with numbered cards and court cards, used for divination and reflection.

In modern English, arcana also appears in phraseology such as arcane meaning hidden, obscure. The plural form arcana is rarely used in everyday speech but common in scholarly or occult contexts. The singular arcanum is rarely used but may appear in historical or fictional work.