Mys-tē'ri-ous, a.

a. [Fr. mystérieux, It. & Sp. misterioso.] Relating to, partaking of the nature of, or containing, mystery; difficult or impossible to understand; obscure; not revealed or explained.

God at last To Satan, first in sin, his doom applied, Though in mysterious terms. Milton.

Synonyms—Obscure; secret; occult; dark; mystic; cabalistic; enigmatical; unintelligible; incomprehensible.