Usage Note
Mystérieusement is formed regularly from mystérieux/mystérieuse + -ment. It modifies verbs and adjectives to indicate something happened in a mysterious or unexplained way. The related adjective mystérieux/mystérieuse and the noun mystère (m) share the same family. It appears frequently in crime fiction and news reports about unexplained events.
Examples
"Il a mystérieusement disparu hier soir."
Natural Translation
He mysteriously disappeared last night.

Free starter pack
Building your French vocabulary?
Get the 100 most common French words as a free PDF — one email, no spam.
Related Words
Explore French by topic
FrenchNow
7 min read