From Longman Dictionary of Contemporary Englishmysteriousmys‧te‧ri‧ous /mɪˈstɪəriəs $ -ˈstɪr-/ ●●○ adjective 1 MYSTERIOUSmysterious events or situations are difficult to explain or understand The police are investigating the mysterious deaths of children at the hospital. Benson later disappeared in mysterious circumstances. There’s something mysterious going on.► see thesaurus at strange2 MYSTERIOUSa mysterious person is someone who you know very little about and who seems strange or interesting SYN enigmatic I decided to find out more about my mysterious new neighbour. a mysterious stranger3 TELL A SECRETsomeone who behaves in a mysterious way says very little about what they are doing SYN secretivemysterious about Helen’s being very mysterious about her plans. She hid her thoughts behind a mysterious smile. —mysteriously adverb Jackson had mysteriously disappeared.THESAURUSmysterious difficult to explain or understand, and often strange or slightly frighteningthe mysterious disappearance of ships in the waters of the Bermuda TriangleWhat’s that mysterious noise?puzzling difficult to explain or understandAt first this must seem a puzzling question.I found her attitude deeply puzzling.baffling impossible to understand, so that you feel very confusedIt was a baffling case.Like many people, I find theoretical physics baffling.inexplicable formal impossible to explainFor some inexplicable reason her mind went completely blank.Some things in life are inexplicable.enigmatic formal mysterious and difficult to understand, but also often attractive or interesting – used especially about people, their expressions, or things they sayShe gave him an enigmatic smile.an enigmatic remarkcryptic formal having a meaning that is difficult to understand, and is not expressed in a clear direct way – used especially about things that people say or writeI got a rather cryptic message from him.cryptic commentsbe a mystery if something is a mystery, you cannot understand how or why it happensFour years later, his death remains a complete mystery.It’s all a mystery to me.be shrouded/veiled in mystery if an event or a situation, especially one that happened a long time ago, is shrouded in mystery, it is mysterious because no one knows exactly what happenedStone age civilization, veiled in mystery as it is, has provided the greatest challenge to historians.
Examples from the Corpus
mysterious• He was an impostor -- dark, frightening and mysterious.• He was seen leaving the building at midnight with two men -- it was all very mysterious.• There was something mysterious about him, and she wanted to ask him a lot of questions.• Ishmael suggests that various primitive tribes and various religions have always looked upon the sea as something mysterious and deep.• The witch: An evil, mysterious character, with the classic, repulsive look of a witch.• The ship vanished in mysterious circumstances, never to be seen again.• Two weeks later, the shop burned to the ground under mysterious circumstances.• Hidden along each Trail are nine mysterious clues.• Police are investigating the mysterious disappearance of a young schoolteacher.• No one could offer an explanation for his mysterious disappearance.• She had been suffering from mysterious fits for five years before the doctors diagnosed epilepsy.• You are a mysterious girl -- why won't you tell me your name?• He will bear a parcel from the mysterious, lovely, no-place-jacketed Carolina.• All of them with a tap root deep in history and branches lost in mysterious mist.• Now he concentrated on the mysterious murders in the forest.• At all times all wise men had revered the mysterious organ of generation through which alone might life be entered.• a woman with a mysterious past• I kept getting mysterious phone calls where the caller would hang up as soon as I answered.• The General was killed in a mysterious plane crash.• When the whale is cut up, the head resembles that of the mysterious Sphynx.• Who killed the mysterious visitor to Pine Valley?in mysterious circumstances• Eight others connected directly or indirectly with the dig later died in mysterious circumstances.• The defendants stored on their land large quantities of combustible materials which ignited in mysterious circumstances.• Some one has been murdered in mysterious circumstances: how has it come about?mysterious about• Nelligan was mysterious about whom she modeled the character on. 