the layer of the earth's atmosphere above the troposphere, extending to about 50 km above the earth's surface (the lower boundary of the mesosphere) 平流层,同温层 ■(figurative)the very highest levels of a profession or other sphere, or of prices or other quantities (喻)(职业或别的领域、价格或别的数量)最高档,最高级;最上层;最高部位 her next big campaign launched her into the fashion stratosphere. 她接下来的一个大型活动使她进入时装界的上流阶层。