mystērion (English spelling) mysterion

Japanese: mystērion（英語表記）mysterion

...One of the basic terms in Christianity. When the Greek word mystērion from the Bible was translated into Latin, it was sometimes written as mysterium, but on the other hand, the Latin word sacramentum, which was used in the military as a ceremonial term and has the meaning of a legal oath, was also used as a translation of mysterion from the time of Tertullian (died around 225), and this later became the origin of theological terms in European and American languages. In Japan, Christianity is also translated in various ways depending on the church, such as sacrament (Catholic), sacrament, holy sacrament (Protestant), sacrament (Anglican Church), and mystery (Christ Orthodox Church).

From [Mysteries]

…Generally, it refers to a religious ceremony that is kept secret from non-believers. In Greek, it is called mystērion, which comes from myein, meaning to close one's eyes or mouth. Many religions, especially in ancient Greece and Rome, were characterized by the performance of such secret rituals. …

*Some of the terminology that mentions "mystērion" is listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

Japanese:

…キリスト教の基本用語の一つ。聖書ギリシア語のミュステリオンmystērionということばがラテン語に訳されたとき，そのままラテン書きにされてミュステリウムmysteriumとされる場合もあったが，一方儀礼用語として軍隊でも使われ，法的誓約の意味を含むラテン語のサクラメントゥムsacramentumもテルトゥリアヌス(225ころ没)のころからミュステリオンの訳語として用いられ，これが後に神学用語として欧米諸語の語源となった。日本では，キリスト教でも教会によって秘跡(カトリック)，礼典，聖礼典(プロテスタント)，聖奠（てん）(聖公会)，機密(ハリストス正教会)などとさまざまに訳されている。…