同义词

a. unscalable，unsurmountable

反义词

a.   scalable

参考例句

1. Oscillations could render the escalator unclimbable, and it may be a terrorist target.
震动会使电梯不可攀爬，并且它可能会成为恐怖分子的袭击目标。
2. Several mountains were believed unclimbable, and many dare-takers and adventurers did nothing but prove this theory again and again by tumbling from their peaks to a jagged death.
一些山脉据信是不能攀登的，许多胆大者和冒险家没有做成任何事情只是通过从山脉的顶端跌落摔成粉身碎骨而一遍又一遍的证明了这个理论。

英英解释

adj.
  1. incapable of being ascended
  2. incapable of being surmounted or climbed

网络释义

unclimbable
爬不上去;