Definition of mysterious

The word "mysterious" has its origins in the 15th century, derived from the Middle English word "mystery", which means "a secret or hidden thing". This, in turn, comes from the Old French word "mistere", meaning "secret" or "hidden", which is derived from the Latin word "misterium", meaning "secret" or "(hidden) thing". The word "mysterious" originally referred to something that was obscure or difficult to understand, often due to its secrecy or hidden nature. Over time, the meaning of the word expanded to include connotations of nuance, subtlety, and often, an air of mystery or intrigue. Today, "mysterious" is often used to describe something that is puzzling, enigmatic, or difficult to explain, and is often applied to phenomena, events, or individuals that are shrouded in secrecy or uncertainty.