Those who would, as it were, force a passage to his heart, found an impassable barrier.

He meets a woman who shares his ideals, only to find that the past places what seems to be an impassable barrier between them.

Should the river narrow, it would soon form an impassable barrier.

The midrib forms an impassable barrier except at its upper end.

For thousands of years the Sahara had been an impassable barrier, a bit like it is now.

In some cases, a wall may refer to an individual's debilitating mental or physical condition, seen as an impassable barrier.

The soldiers standing behind them formed an impassable barrier.

To either side the mountains presented an impassable barrier to men on foot.

And with it the knowledge that whatever else might have happened, the impassable barriers which held them apart still stood.

Without the surface plasmon, that would be an impassable barrier to light.