Envelope meaning

noun

1. a flat (usually rectangular) container for a letter, thin package, etc.

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 (especially an aircraft)

   “test pilots try to push the envelope”

6. the bag containing the gas in a balloon

   Synonymsgasbag