treacherous

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

• IPA^(key): /ˈtɹɛt͡ʃəɹəs/, /ˈtɹɛt͡ʃɹəs/

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treacherous (comparative more treacherous, superlative most treacherous)

1. Exhibiting treachery.
   • 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 […]

2. Deceitful; inclined to betray.
3. Unreliable; dangerous.

   a treacherous mountain trail

   • 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.

• (antonym(s) of “exhibiting treachery”): loyal

• “treacherous”, in Webster’s Revised Unabridged Dictionary, Springfield, Mass.: G. & C. Merriam, 1913, →OCLC.
• “treacherous”, in The Century Dictionary […], New York, N.Y.: The Century Co., 1911, →OCLC.
• “treacherous”, in OneLook Dictionary Search.