Arcanum

Srkan'um, n. a secret a mystery: pi. Aroan'a. 1 arcanus, secret, closed— area a chest,] Arch, arch, *. a construction of stones or other materials, arranged in the line of a curve, so as by mutual pre ure to support each other. v.t to cover with an arch to bend into the form of an arch. [From Fr. arc, as ditch is from dyke —L. arcus a bow.]