faithless applies to any failure to keep a promise or pledge or any breach of allegiance or loyalty.
faithless allies
false stresses the fact of failing to be true in any manner ranging from fickleness to cold treachery.
betrayed by false friends
disloyal implies a lack of complete faithfulness to a friend, cause, leader, or country.
disloyal to their country
traitorous implies either actual treason or a serious betrayal of trust.
traitorous acts punishable by death
treacherous implies readiness to betray trust or confidence.
a treacherous adviser
perfidious adds to faithless the implication of an incapacity for fidelity or reliability.
a perfidious double-crosser
Example Sentences
a treacherous act of betrayal They were not prepared to hike over such treacherous terrain. The snow made their hike all the more treacherous. Discussions about money can lead couples into treacherous territory.
Recent Examples on the WebMonsoon rains this year have been particularly treacherous for residents of the cross-border communities. José Ignacio Castañeda Perez, The Arizona Republic, 26 Aug. 2022 While the Netherlands’ transportation system famously accommodates bicycles, many communities are treacherous for older folks on foot. Robert Weisman, BostonGlobe.com, 18 Aug. 2022 Bernie still walks the chalet waiting for the big blasts, though the slide is a bit more treacherous, as Vassegh demonstrated. Jr Radcliffe, Journal Sentinel, 18 Aug. 2022 And the party itself is a minefield of potential gaffes, made more treacherous by most yards’ dearth of shelter. Nina Molina, WSJ, 7 July 2022 All of which makes the Fed’s inflation-taming, recession-avoiding act even more treacherous. Paul Wiseman, Chicago Tribune, 16 June 2022 All of which makes the Fed’s inflation-taming, recession-avoiding act even more treacherous. Paul Wiseman, The Christian Science Monitor, 16 June 2022 Threat of Prosecution For women seeking abortions in Poland — and those trying to assist them — the routes have become treacherous.New York Times, 12 June 2022 But the undue optimism from the White House about what is possible with a 50-50 Senate has made a difficult political terrain even more treacherous to navigate. Walter Shapiro, The New Republic, 2 June 2022 See More