thermosphere.

A high layer of a planet's atmosphere where temperature generally rises with altitude as gas absorbs energetic radiation.

Use it for

Words that belong together

• Earth's thermosphere
• lower thermosphere

On the page

The capsule crossed the thermosphere before the denser air began to slow it sharply.

Usage notes

Primary category: sci-fi. Forms: Singular thermosphere; plural thermospheres. Legacy lexical fields mirror sense 1 only. Use numbered sense fields for all meanings. Established modern English lexical item. No separate regional spelling or grammatical inflection entry. Commonness: moderately common.