envelope

[en-vuh-lohp, ahn-] /ˈɛn vəˌloʊp, ˈɑn-/
noun
1.
a flat paper container, as for a letter or thin package, usually having a gummed flap or other means of closure.
2.
something that envelops; a wrapper, integument, or surrounding cover.
3.
Biology. a surrounding or enclosing structure, as a corolla or an outer membrane.
4.
Geometry. a curve or surface tangent to each member of a set of curves or surfaces.
5.
Radio. (of a modulated carrier wave) a curve connecting the peaks of a graph of the instantaneous value of the electric or magnetic component of the carrier wave as a function of time.
6.
the fabric structure enclosing the gasbag of an aerostat.
7.
the gasbag itself.
8.
Electronics. the airtight glass or metal housing of a vacuum tube.
9.
the technical limits within which an aircraft or electronic system may be safely operated.
Idioms
10.
push the envelope, to stretch established limits, as in technological advance or social innovation.
Also, envelop.
Origin
1700-10; < French enveloppe, derivative of envelopper to envelop
Can be confused
envelop, envelope.
Examples from the web for envelope
  • One thing that separates mere stamps from postal history is the evocativeness of an envelope or postcard.
  • Please include a self-addressed envelope for return of work samples.
  • Some of those who are thought to be listed in the sealed envelope have keenly endorsed the idea of a tribunal.
  • Hold the guide envelope firmly in the center with one hand, and use a pencil or pen to trace around it.
  • The part of the sound wave encoded by the implant to represent speech is known as the envelope.
  • Then insert your invitation into the envelope with the text facing the flap side.
  • Do not toss out any unfamiliar white envelope without giving it the once-over.
  • Please specify on envelope the reference of the post being applied for.
  • At one point he handed each attendee an unmarked brown envelope.
  • Please make sure to apply appropriate postage to the return envelope.
British Dictionary definitions for envelope

envelope

/ˈɛnvəˌləʊp; ˈɒn-/
noun
1.
a flat covering of paper, usually rectangular in shape and with a flap that can be folded over and sealed, used to enclose a letter, etc
2.
any covering or wrapper
3.
(biology) any enclosing structure, such as a membrane, shell, or skin
4.
the bag enclosing the gas in a balloon
5.
(maths) a curve or surface that is tangent to each one of a group of curves or surfaces
6.
(electronics) the sealed glass or metal housing of a valve, electric light, etc
7.
(telecomm) the outer shape of a modulated wave, formed by the peaks of successive cycles of the carrier wave
8.
(informal) push the envelope, to push the boundaries of what is possible
Word Origin
C18: from French enveloppe, from envelopper to wrap around; see envelop; sense 8 from aeronautics jargon, referring to graphs of aircraft performance
Word Origin and History for envelope
n.

1705, from French enveloppe (13c.), a back-formation from envelopper "to envelop" (see envelop).

envelope in Medicine

envelope en·ve·lope (ěn'və-lōp', ŏn'-)
n.
An enclosing structure or cover, such as a membrane or the outer coat of a virus.