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

In the world of legal services ads, which have a history of pushing the envelope, some are concerned that the rapidly advancing AI makes it easier to skirt restrictions.

Read more on Los Angeles Times

“I just wanted to push the envelope in that situation since we hadn’t had anything going on since the first inning.”

Read more on Los Angeles Times

“This is not stretching the envelope,” he said.

Read more on Salon

Complete your ballot, put it in the provided envelope and sign the back.

Read more on Los Angeles Times

The envelope rule was introduced when European players were allowed to enter the biennial contest against the US in 1979.

Read more on BBC

Related Words

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