New word. Loved it so much, I wanted to give to you too.
arcanum \ar-KAY-nuhm\, noun;
plural arcana \-nuh\:
1. A secret; a mystery.
2. Specialized or mysterious knowledge, language, or information that is not accessible to the average person (generally used in the plural).
Arcanum is from the Latin, from arcanus "closed, secret," from arca, "chest, box," from arcere, "to shut in."
Here we must enter briefly into the technical arcana of employment law.
-- Paul F. Campos, JurismaniaThe Madness of American Law