Inertia coupling was essentially unknown before the introduction of high-speed jet aircraft.

He was now in a part of the Grand Palace which was essentially unknown to him.

In such a world, magic works and spirits are real, but modern science and technology are essentially unknown.

Up to the middle of the 17th century, corridors were essentially unknown.

Simeus was essentially unknown in Haiti prior to 2004 and many viewed him as an outsider.

Being only known from fossils, its behavior and the exact reasons for its extinction are essentially unknown.

It is essentially unknown in the rest of the world.

Now you are adding two salt sources of essentially unknown composition.

The biology of these species is essentially unknown, and their larvae have never been seen.

Yet, unlike Osama bin Laden, he has remained essentially unknown.