envelope

American  

[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.

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idioms

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

envelope British  

/ 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

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Etymology

Origin of envelope

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

Example Sentences

“Secure ballot envelope identifiers provide a reliable, auditable mechanism to enforce Federal law without unduly burdening or infringing on the rights of eligible voters,” the order reads.

From Los Angeles Times

Once the mail’s sorted, I turn on the computer to check the marina’s email and notice another envelope that I missed, wedged behind the monitor.

From Literature

The post included a clip of the comedian performing at the Laugh Factory when a manila envelope is tossed onstage.

From Los Angeles Times

It is not simply that the curators have tidied up before letting the public in: Woolf’s “writing lodge” at Monk’s House in Sussex, England, for instance, is suspiciously clear of crumpled envelopes and broken cigarette-holders.

From The Wall Street Journal

Back of the envelope, each one might be worth about $10 million.

From The Wall Street Journal

Related Words

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