An envelope is the paper container used to hold a letter being sent by post.

Envelope may also refer to:

Mathematics

  • Envelope (mathematics), a curve, surface, or higher-dimensional object defined as being tangent to a given family of lines or curves (or surfaces, or higher-dimensional objects, respectively)
  • Envelope (category theory)

Science

  • Viral envelope, the membranal covering surrounding the capsid of a virus
  • Cell envelope of a bacterium, consisting of the cell membrane, cell wall and outer membrane
  • , the fabric skin covering the airship
  • Building envelope, the exterior layer of a building that protects it from the elements
  • Envelope (motion), a solid representing all positions that an object may occupy during its normal range of motion
  • Envelope (music), the variation of a sound over time, as is used in sound synthesis
  • Envelope (radar), the volume of space where a radar system is required to reliably detect an object
  • Envelope (waves), a curve outlining the peak values of an oscillating waveform or signal
  • Envelope detector, an electronic circuit used to measure the envelope of a waveform
  • Flight envelope, the limits within which an aircraft can operate

Entertainment

  • Envelopes (band), an indie/pop band from Sweden and France, based in the UK
  • Envelope (film), a 2012 film
  • "Envelopes", a song by Frank Zappa from his 1982 album Ship Arriving Too Late to Save a Drowning Witch

Other uses

  • Envelope (military), attacking one or both of the enemy's flanks to encircle the enemy
  • The envelope of an internet email, its SMTP routing information
  • Envelope system, a method of personal budgeting where money is allocated for specific purposes
  • Gaza envelope, a region in southwestern Israel adjacent to the Gaza Strip

See also

  • Two envelopes problem, a paradox
  • Stellar envelope (disambiguation), for astrophysics uses