impassably
/ˌɪmˈpæsəbli/not passable; not allowing passage over, through, along, etc.
adverb [方式副词] 无法通行地，不能通行地
The road was impassably flooded after the heavy rain, so we had to find an alternative route. 大雨过后，这条路淹得无法通行，所以我们不得不另寻一条路。
