envelope

[en-vuh-lohp, ahn-]

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.

envelope

/ ˈɒn-, ˈɛnvəˌləʊp /

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,  to push the boundaries of what is possible

Word History and Origins

Origin of envelope¹

1700–10; < French enveloppe, derivative of envelopper to envelop

Word History and Origins

Origin of envelope¹

C18: from French enveloppe, from envelopper to wrap around; see _envelop ; sense 8 from aeronautics jargon, referring to graphs of aircraft performance

Idioms and Phrases

Idioms

1. push the envelope, to stretch established limits, as in technological advance or social innovation.

Example Sentences

When the brown envelopes arrived at Short's door, his tax liability was shown to be £1.6m.

From BBC

He would push the envelope, and Freeman would rein him back in if need be.

From Los Angeles Times

But though “Lurker” could certainly push the envelope further, Matthew’s ascent, fall from grace and gradual climb back up wouldn’t feel as realistic as it needs to for the film to land its sickly ending.

From Salon

She believes a special day out, or being allowed to redecorate their bedroom or host some family or friends can be a far more powerful reward than "cash in an envelope".

From BBC

Not a photocopied handout in English tucked into an envelope behind a paycheck, not a rushed talk in Spanish at the field’s edge, but a verified safety course — certified by labor contractors and farmers alike.

From Los Angeles Times

Related Words

• bag 
• box 
• casing 
• coat 
• container 
• jacket 
• pocket 
• pouch