treacherous

comparative more treacherous · superlative most treacherous

1. Exhibiting treachery.

   I see the wife misused by her husband, I see the treacherous seducer of young women, / I mark the ranklings of jealousy and unrequited love attempted to be hid […]

   1855, Walt Whitman, Leaves of Grass

   Antonyms: loyal

2. Deceitful; inclined to betray.

   Synonyms: Judaslike, perfidious, traitorous, beguiling, deceitful, deceptious, deceptive, deceptory

3. Unreliable; dangerous.

   a treacherous mountain trail

   4 more examples

   Work on the muskeg resulted in the formation in the first instance, and later in lengths of newly-laid track disappearing without trace into the treacherous bog.

   1959 March 28, “New Railways in Quebec”, in Railway Magazine, page 202

   […] they stood in the region of perpetual snow, amidst the glittering, treacherous glaciers and crevasses, with vast slippery-pathed precipices yawning round.

   2002, Charles Morris, The San Francisco Calamity

   There are many treacherous paths leading toward history’s realms of darkness, but when it comes to routes hacked out by imperialist powers in the Congo, we really do seem near darkness’s heart.

   2009 March 30, Edward Rothstein, “Casting a Sliver of Light on the Heart of Darkness”, in The New York Times, archived from the original on 27 Jul 2020

   It is standard practice for search and rescue authorities to ask other vessels in the area to assist. Usually, this is done. The weather on the night of 31 December was too atrocious, and when at 11pm the Coast Guard asked the crabber Ruff & Reddy to head to the scene, its skipper refused, as a skipper has a right to do if he believes conditions to be too treacherous.

   2025 October 21, Rose George, “‘I knew in my head we were dying’: the last voyage of the Scandies Rose”, in The Guardian, archived from the original on 18 Dec 2025

   Synonyms: hazardous, perilous, unsound, dangerous, dangersome, hazardous, hot, jeopardous