See examples of mysterious used in a sentence. How to use mysterious in a sentence. Meaning, pronunciation, picture, example sentences, โ€ฆ Full of, characterized by, or involving mystery. The meaning of mysterious is of, relating to, or constituting mystery. He died in mysterious circumstances. This is reminiscent of the extraordinary relationship which amputees develop with their artificial replacements, revealing a whole inner โ€ฆ Definition of mysterious adjective in oxford advanced learners dictionary. Someone or something that is mysterious is strange and is not known about or understood.