a flat paper container with a sealable flap, used to enclose a letter or document
信封。
a covering or containing structure or layer
封皮,封套;外表,外壳;包裹物
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the external envelope of the swimming pool .游泳池的外罩。
the outer metal or glass housing of a vacuum tube, electric light, etc.
(真空管或电灯等的)泡。
the structure within a balloon or non-rigid airship containing the gas
(气球或软式飞艇的)气囊。
【微生物】 包膜,外膜,被膜。
【电子】 包络(曲) 线。
【数】 包络线(或面)。
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the back of an envelope used to denote calculations or plans of the most sketchy kind (指估计或计划)最粗略的一类a proposal drawn up on the back of an envelope . 一项草拟的粗略提议 -
push the envelope (或the edge of the envelope )informal approach or extend the limits of what is possible 〈非正式〉 接近(或达到)极致these are extremely witty and clever stories that consistently push the envelope of TV comedy . 这些故事极其诙谐和巧妙,总是将电视喜剧推向极致 -
[ORIGIN originally aviation slang, relating to graphs of aerodynamic performance.]
"mid 16th cent. (in the sense ‘wrapper, enveloping layer'; originally as