treacherously

American  

[trech-er-uhs-lee] / ˈtrɛtʃ ər əs li /

adverb

1. in a way characterized by faithlessness or betrayal; traitorously.

   Darius of Persia was treacherously wounded by two of his own officers.

2. in a way that is deceptive, untrustworthy, or unreliable.

   This peak looks treacherously easy, but it has seen a recurrence of avalanches.

3. in a way or to a degree that is dangerous; hazardously.

   He refused to go faster than 25 mph on the treacherously winding and narrow Wildwood Road.

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Other Word Forms

• untreacherously adverb

Etymology

Origin of treacherously

treacherous ( def. ) + -ly

Example Sentences

Other notable singers included bass-baritone Robert Frazier as the Rev. John Hale, who realizes the truth too late, and soprano Kresley Figueroa as the treacherously weak-willed Mary Warren.

From The Wall Street Journal • Mar. 23, 2026

A storm blew in, drenching the stadium and making the shot put ring treacherously slippery.

From Los Angeles Times • Aug. 4, 2024

The playing surface was treacherously slippy with snow piled up around up around the touchlines and conditions barely playable.

From BBC • Sep. 11, 2023

In a statement late Friday, he said he was ready to find a compromise but “they have treacherously cheated us.”

From Washington Times • Jun. 24, 2023

I didn’t want to rely on her kindness, especially not now, when death felt treacherously close.

From "The City Beautiful" by Aden Polydoros