From French enveloppe.

• (RP) IPA: /ˈɛnvələʊp/, /ˈɒnvələʊp/, /ˈɒnvləʊp/, /ˈɑ̃vələʊp/
• (General American) enPR: ĕn′vəlōp', än′vəlōp', IPA: /ˈɛnvəˌloʊp/, /ˈɑn-/, /-lop/

envelope (plural envelopes)

1. A paper or cardboard wrapper used to enclose small, flat items, especially letters, for mailing.
2. Something that envelops; a wrapping.

   Synonyms: wrapper

3. A bag containing the lifting gas of a balloon or airship; fabric that encloses the gas-bags of an airship.

   Synonyms: gasbag

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. (networking) The information used for routing a message that is transmitted with the message but not part of its contents.

   Synonyms: header

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.

   push the envelope

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.

• French: enveloppe
• German: Briefumschlag, Umschlag
• Italian: busta
• Portuguese: envelope
• Russian: конве́рт
• Spanish: sobre

• German: Umschlag
• Portuguese: invólucro
• Russian: обёртка

• German: Hülle
• Portuguese: envelope
• Russian: оболо́чка

• French: enveloppe
• German: Hüllkurve
• Russian: огиба́ющая

• Russian: огиба́ющая

• Russian: огиба́ющая

• Russian: оболо́чка

envelope (envelopes, present participle enveloping; simple past and past participle enveloped)

1. (transitive, rare) To put (something) in an envelope.

See envelop.

• enPR: ĕn-vĕl'əp, IPA: /ɛnˈvɛləp/

envelope (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.