arcane: [16] Arcane comes from the Latin adjective arcānus ‘hidden, secret’. This was formed from the verb arcēre ‘close up’, which in turn came from arca ‘chest, box’ (source of English ark). The neuter form of the adjective, arcānum, was used to form a noun, usually used in the plural, arcāna ‘mysterious secrets’. => ark[arcane etymology, arcane origin, 英语词源]