IPA: /ɪmˈpæsəblɪ/
KK: /ɪmˈpæsəblɪ/
In a way that cannot be passed or crossed; not able to be traveled through.
The road was blocked, and we had to turn back because it was impassably covered in snow.
Impassably → It is formed from "im-" (meaning not) and "passable" (from Latin "passabilis", meaning able to be passed). The word "impassably" means in a manner that cannot be passed or traversed.
Think of 'not able to be passed' — 'im-' means not, and 'passable' means able to be passed.