a.

1. 背叛的；不忠的；奸詐的
   He was cruel, treacherous and unscrupulous.

   他殘忍、奸詐、不擇手段。

2. 不牢靠的；危險的；變化莫測的
   My memory is treacherous.

   我的記憶不可靠了。

adj.

1. guilty of or involving betrayal or deception.
2. (of ground, water, conditions, etc.) having hidden or unpredictable dangers.