envelope

From French enveloppe. The engineering sense is derived from flight envelope.

• (Received Pronunciation) IPA^(key): /ˈɛn.və.ləʊp/, (chiefly senses 1 and 2) /ˈɒn.və.ləʊp/, /ˈɑ̃.və.ləʊp/[1]

• Audio 1 (UK)

  (file)

• Audio 2 (UK)

  (file)

• (General American) enPR: ĕn′vəlōp', än′vəlōp'; IPA^(key): /ˈɛn.vəˌloʊp/, /ˈɑn.vəˌloʊp/

• Audio 1 (US)

  (file)

• Audio 2 (US)

  (file)

envelope (plural envelopes)

1. A paper or cardboard wrapper used to enclose small, flat items, especially letters, for mailing.
   • 2013 June 14, Jonathan Freedland, “Obama's once hip brand is now tainted”, in The Guardian Weekly, volume 189, number 1, page 18:

     Now we are liberal with our innermost secrets, spraying them into the public ether with a generosity our forebears could not have imagined. Where we once sent love letters in a sealed envelope, or stuck photographs of our children in a family album, now such private material is despatched to servers and clouds operated by people we don't know and will never meet.

2. Something that envelops; a wrapping.
3. A bag containing the lifting gas of a balloon or airship; fabric that encloses the gas-bags of an airship.
   • 1992, Lieutenant Colonel Donald E. Ryan, Jr, The airship's potential for intertheater and intratheater airlift, DIANE Publishing, page 46:

     They have no internal or external support structure, being simply a fabric bag (or envelope) filled with a lighter than air gas. Inside the envelope are one or more "ballonets", or smaller bags, which help maintain the envelope's shape.

4. (geometry) A mathematical curve, surface, or higher-dimensional object that is the tangent to a given family of lines, curves, surfaces, or higher-dimensional objects.
5. (electronics) A curve that bounds another curve or set of curves, as the modulation envelope of an amplitude-modulated carrier wave in electronics.
6. (music) The shape of a sound, which may be controlled by a synthesizer or sampler.
7. (computing) The information used for routing a message that is transmitted with the message but not part of its contents.
8. (biology) An enclosing structure or cover, such as a membrane; a space between two membranes
9. (engineering) The set of limitations within which a technological system can perform safely and effectively.
10. (astronomy) The nebulous covering of the head or nucleus of a comet; a coma.
11. An earthwork in the form of a single parapet or a small rampart, sometimes raised in the ditch and sometimes beyond it.
    • 1816, James Stanier Clarke, The Life of James the Second King of England:

      make a blind all along the bottom of the ditch of the Envelope

• (something that envelops): wrapper
• (bag containing the lifting gas): gasbag

• Wikipedia article on envelopes used for mailing
• Wikipedia article on envelopes in geometry

See envelop.

• enPR: ĕn-vĕl'əp, IPA^(key): /ɛnˈvɛləp/
• for audio, see envelop

envelope (third-person singular simple present envelopes, present participle enveloping, simple past and past participle enveloped)

1. Archaic form of envelop.
   • 1877, James Booth, A Treatise on Some New Geometrical Methods (page 209)

     Again, if the plane of the impressed couple intersects the mean plane between N and C, it will envelope the cone whose focals are ON, ON′, and whose internal axis is therefore OA.

Borrowed from French enveloppe, from envelopper.

• Hyphenation: en‧ve‧lo‧pe

envelope m (plural envelopes)

1. envelope