From a commercial and industrial standpoint a most important class of pump is that known as the compression type; in these, air or any other gas is compressed rather than rarefied.

In our study of the atmosphere we saw that air can be compressed and rarefied; in other words, we saw that air is very elastic.

But we must tread lightly in these rarefied regions and get on to more practical concerns.

The sensation reminded me of my only experience of mountaineering, and from that I judged the air to be more rarefied than it is now.

Owing to the rarefied atmosphere (low air pressure) at high altitude, less oxygen is breathed in and many travellers experience altitude sickness or acute mountain sickness.

In the opening chapter, Hans is symbolically transported away from the familiar life and mundane obligations he has known, in what he later learns to call "the flatlands", to the rarefied mountain air and introspective little world of the sanatorium.

Hans Castorp’s stay in the rarefied air of "The Magic Mountain" thus provides him with a panoramic view of pre-war European civilization and its discontents.

Surrounding and stretching between galaxies, there is a rarefied plasma that is organized in a galactic filamentary structure.

Computer simulations and observations indicate that up to half of the atomic matter in the Universe might exist in this warm-hot, rarefied state.

When a party of slinkers undermines his shack, Calthorpe and Neilan flee into the Idiots' Hills, hoping the slinkers cannot follow them into the rarefied atmosphere.

In its dispersed, rarefied state, qi is invisible and insubstantial, but when it condenses it becomes a solid or liquid and takes on new properties.