The mesosphere is the layer of Earth's atmosphere located between the stratosphere and the thermosphere. It is characterized by extremely low temperatures and atmospheric pressure that decreases with height. Synonyms for the mesosphere include middle atmosphere and third layer, as it is the third layer from Earth's surface. It is also commonly referred to as the mesopause region, as this is the transition point between the mesosphere and the thermosphere. Additionally, some scientific textbooks may use other terms such as intermediate atmosphere or mid-atmosphere to describe this layer, although these synonyms are less commonly used. Overall, the mesosphere is a significant and distinct layer of Earth's atmosphere, with several synonym options available for referencing it.