1. A secret.

Nuttall's Standard dictionary of the English language By Nuttall, P.Austin

• arcanu,
• zrcanum,
• srcanum,
• wrcanum,
• qrcanum,
• aecanum,
• adcanum,
• afcanum,
• atcanum,
• a5canum,
• a4canum,
• arxanum,
• arcanium,
• arcannum,
• arkanum,
• arcanem,
• arcaenm,
• arcamun,
• arceinum,
• arcanom

• argon,
• arachnid,
• arachnida,
• arcane,
• archangel,
• arkin,
• Arrasmith,
• arson,
• aragon,
• arcand,
• areca nut,
• arraign,
• arachnoid,
• archean,
• argument,
• arkansan.

The adjective form of the word "arcanum" is "arcane".

The plural of the "arcanum" can be the "arcana".

The plural of the "arcanum" can be the "arcanums".

The singular of the "arcanum" can be the "arcanum".