envelope
- n. 信封，封皮；包膜；[天] 包层；包迹
英英释意
- 1. a flat rectangular paper container for papers
- 2. any wrapper or covering
- 3. a curve that is tangent to each of a family of curves
- 4. a natural covering (as by a fluid);
- "the spacecraft detected an envelope of gas around the comet"
- 5. the maximum operating capability of a system;
- "test pilots try to push the envelope"
- 6. the bag containing the gas in a balloon