English Reference

Word

mysteriously

Phoneticsmys·te·ri·ous·ly

US/ˌmɪsˈtɪɹiəsɫi/

UK/mɪstˈiəɹɪəsli/

Definition

adv. in a way that is strange and difficult to explain. You use this when something happens and you do not know why or how it happened.

adv. in a manner that is difficult or impossible to understand, explain, or identify. Often used to describe events that seem to lack a logical cause.

Examples

“The lights in the old house mysteriously turned on.”

“The ancient documents mysteriously disappeared from the locked safe overnight without any sign of a break-in.”

“The species, which had thrived for centuries in the isolated valley, mysteriously vanished from the fossil record long before the arrival of human settlers.”

Examples

simple

“The lights in the old house mysteriously turned on.”

contextual

“The ancient documents mysteriously disappeared from the locked safe overnight without any sign of a break-in.”

complex

“The species, which had thrived for centuries in the isolated valley, mysteriously vanished from the fossil record long before the arrival of human settlers.”

Usage

Typically placed after the verb or at the end of the clause to describe the nature of an action.

Real-World Examples

“One unusual type is the so-called hot subdwarf—small stars that burn mysteriously hot for their size.”
Phys.org · 3 Sept 2026
“For reasons that will later become clear, De Gaulle’s own story is mysteriously intertwined with that of a hothead young patriot, Fernand Bonnier de la Chapelle (Florian Lesieur), who is De Gaulle’s biggest fan.”
The Guardian · 26 Aug 2026

Etymology

From Middle English misteriusly, equivalent to mysterious + -ly.

Etymology adapted from Wiktionary, available under CC BY-SA 4.0.

Word family

mysteriousAdjectivemysteriouslyAdverbmysteryNoun

This entry

Level
B2 · Upper Intermediate
Frequency
Frequent
Updated

Scan code

englishreference.com/q/mysteriously

English Reference