a.

1. 背叛的；不忠的；奸诈的
   He was cruel, treacherous and unscrupulous.

   他残忍、奸诈、不择手段。

2. 不牢靠的；危险的；变化莫测的
   My memory is treacherous.

   我的记忆不可靠了。

adj.

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