treacherous

English

Etymology

From Old French trecheros, tricheros (“deceitful”), equivalent to treacher +‎ -ous. See treacher.

Pronunciation

IPA^(key): /ˈtɹɛt͡ʃəɹəs/, /ˈtɹɛt͡ʃɹəs/
Audio (US): (file)

Adjective

treacherous (comparative more treacherous, superlative most treacherous)

Exhibiting treachery.
Antonym: loyal
- 1855, Walt Whitman, Leaves of Grass:
  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 […]
Deceitful; inclined to betray.
Synonyms: Judaslike, perfidious, traitorous; see also Thesaurus:deceptive, Thesaurus:treacherous
Unreliable; dangerous.
Synonyms: hazardous, perilous, unsound; see also Thesaurus:dangerous

a treacherous mountain trail
- 1959 March, “New Railways in Quebec”, in Railway Magazine, page 202:
  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.
- 2002, Charles Morris, The San Francisco Calamity:
  […] they stood in the region of perpetual snow, amidst the glittering, treacherous glaciers and crevasses, with vast slippery-pathed precipices yawning round.
- 2009 March 30, Edward Rothstein, “Casting a Sliver of Light on the Heart of Darkness”, in The New York Times‎^[1], archived from the original on 27 July 2020:
  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.
- 2025 October 21, Rose George, “‘I knew in my head we were dying’: the last voyage of the Scandies Rose”, in The Guardian‎^[2], archived from the original on 18 December 2025:
  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.

Derived terms

Related terms

Collocations

treacherous waters
treacherous terrain
treacherous journey
treacherous path
treacherous ground
treacherous road
treacherous place
treacherous part
treacherous sister
treacherous people
treacherous friend
treacherous man
treacherous body
treacherous heart
treacherous mountain
treacherous rocks
treacherous act
treacherous conditions
treacherous currents
treacherous sea
treacherous attack
treacherous murder
treacherous nature
treacherous enemy
treacherous ice
treacherous conduct

Translations

exhibiting treachery

Bulgarian: коварен (bg) (kovaren), вероломен (bg) (verolomen)
Czech: zrádný m
Danish: forræderisk
Dutch: verraderlijk (nl)
Finnish: petollinen (fi)
French: traître (fr)
Georgian: მოღალატური (moɣalaṭuri), გამცემლური (gamcemluri)
German: verräterisch, trügerisch (de)
Greek: προδοτικός (el) m (prodotikós), δόλιος (el) m (dólios)
Ancient Greek: δολερός (dolerós), προδοτικός (prodotikós)
Hungarian: áruló (hu)
Irish: fealltach, cealgach
Old Irish: braittech
Italian: traditore (it) m, sleale (it) m, infido (it) m
Norwegian:
Bokmål: forrædersk
Polish: zdradziecki (pl)
Portuguese: fementido (pt), traiçoeiro (pt) m
Russian: вероло́мный (ru) (verolómnyj), преда́тельский (ru) (predátelʹskij)
Spanish: traicionero (es), alevoso (es), aleve (es)
Swedish: förrädisk (sv), trolös (sv)
Turkish:
Ottoman Turkish: صداقتسز (sadakatsiz)

deceitful; inclined to betray

Azerbaijani: kəmfürsət
Bulgarian: предателски (bg) (predatelski)
Czech: zrádný m
Finnish: petollinen (fi)
French: traître (fr)
Georgian: გამცემლური (gamcemluri)
German: verräterisch, hinterlistig (de), doppelzüngig (de)
Greek: δόλιος (el) m (dólios), επίβουλος (el) m (epívoulos)
Ancient Greek: προδοτικός (prodotikós), δολερός (dolerós)
Hungarian: álnok (hu)
Ingrian: pettelikko, salakavala
Irish: fabhtach, braiteach, cealgach
Kazakh: залым (zalım), опасыз (opasız)
Latin: perfidus (la)
Portuguese: traiçoeiro (pt)
Russian: вероло́мный (ru) (verolómnyj), кова́рный (ru) (kovárnyj)
Turkish:
Ottoman Turkish: صداقتسز (sadakatsiz)

unreliable; dangerous

Bulgarian: ненадежден (bg) (nenadežden)
Czech: zrádný m, ošidný
Danish: forræderisk
Finnish: petollinen (fi)
French: traître (fr)
Georgian: მუხანათური (muxanaturi)
German: tückisch (de)
Greek: ύπουλος (el) m (ýpoulos)
Norwegian:
Bokmål: forrædersk
Plautdietsch: roakboa
Portuguese: traiçoeiro (pt)
Russian: ненадёжный (ru) (nenadjóžnyj), непро́чный (ru) (nepróčnyj)
Spanish: traicionero (es)
Swedish: förrädisk (sv)