Impassable

Impassable describes something that cannot be passed or crossed. It may refer to a physical barrier, such as a cliff or a wall, or to a condition that prevents passage, such as snowdrifts blocking a road. It can also be used figuratively for insurmountable obstacles.

Originates from French impassable, from in- (not) + passable (able to be passed); from the Latin root associated with passare, “to pass.”

In geography, impassable terrain includes features such as sheer cliffs, dense swamps, deserts, or ice fields that cannot be traversed. In transportation, roads or bridges may become impassable due to floods, landslides, heavy snow, or structural damage, sometimes temporarily and other times permanently.

In safety and planning contexts, the term is used to designate routes or passages that cannot be used. Emergency management and civil engineering aim to identify or mitigate impassable segments by providing alternatives, improving infrastructure, or rerouting traffic.

In computing, mapping, robotics, and video games, impassable areas are treated as blocked during pathfinding or navigation. Algorithms and planners are designed to avoid impassable regions when constructing viable routes.

Figuratively, impassable is also used to describe abstract barriers, such as insurmountable disagreements or psychological obstacles, indicating that progress or understanding cannot be achieved through the blocked path.