Definition of "treacherous" []

• Marked by betrayal of fidelity, confidence, or trust; perfidious. See Synonyms at faithless. (adjective)
• Not to be relied on; not dependable or trustworthy. (adjective)
• Marked by unforeseen hazards; dangerous or deceptive: treacherous waters. (adjective)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "Unless the guides were treacherous, he must sight the minarets of El Obeid soon _Unless the guides were treacherous_!"
• "Infuriated by what he calls a treacherous and unacceptable provocation from the diplomatic mission, Cuban communist leader, Fidel Castro began building his response a few days later."
• "Our noble captain did not get rid of his angry looks for some days, and actually wept at what he termed the treacherous conduct of the Admiralty."