envelope

noun

en·​ve·​lope ˈen-və-ˌlōp  ˈän- 

1

: a flat usually paper container (as for a letter)

2

: something that envelops : wrapper

the envelope of air around the earth

3

a

: the outer covering of an aerostat

b

: the bag containing the gas in a balloon or airship

4

a

: a natural enclosing covering (such as a membrane, shell, or integument)

b

: a lipoprotein unit membrane that forms the outer layer of some virions

5

a

: a curve tangent to each of a family of curves

b

: a surface tangent to each of a family of surfaces

6

: a set of performance limits (as of an aircraft) that may not be safely exceeded

also : the set of operating parameters that exists within these limits

7

: a conventionally accepted limit

new computers that push the envelope

How do you pronounce envelope?: Usage Guide

The \ˈen-\ and \ˈän-\ pronunciations are used with about equal frequency, and both are fully acceptable, though the \ˈän-\ version is sometimes decried as "pseudo-French." Actually \ˈän-\ is exactly what one would expect to hear when a French word like entrepreneur is becoming anglicized. Envelope, however, has been in English for nearly 300 years, plenty of time for it to become completely anglicized and for both of its pronunciations to win respectability.

Examples of envelope in a Sentence

Recent Examples on the Web

The aircraft recently completed flight-test campaigns in France and has accumulated more than 100 flight hours as Schiebel continues expanding its operational envelope. —Kaif Shaikh, Interesting Engineering, 6 June 2026

This time the Audi techs have pushed the Vorsprung durch Technik envelope further, with extra performance and tech even denied to the Lambo… plus that extraordinary carbon-fiber body design. —New Atlas, 5 June 2026

Harriet, a National Health Service nurse, was seen hugging a guest and holding an envelope outside the church on Friday. —Stephanie Petit, PEOPLE, 5 June 2026

The process of counting mail-in ballots and validating voters' signatures is also arduous, as each envelope signature must match the signatures on file, which can lead to additional delays. —Emily Chang, ABC News, 4 June 2026

Word History

First Known Use

circa 1714, in the meaning defined at sense 1

Phrases Containing envelope

• back-of-the-envelope
• floral envelope
• pay envelope
• push the envelope
• return envelope
• window envelope

Rhymes for envelope

• antelope
• bronchoscope
• cantaloupe
• cystoscope
• endoscope
• epitope
• gyroscope
• horoscope
• isotope
• microscope
• misanthrope
• pericope

Kids Definition

envelope

noun

en·​ve·​lope ˈen-və-ˌlōp  ˈän- 

1

: a flat usually paper container (as for a letter)

2

: something that envelops

3

: the bag containing the gas in a balloon or airship

4

: a natural enclosing covering (as a membrane)

Medical Definition

envelope

noun

en·​ve·​lope ˈen-və-ˌlōp  ˈän- 

: a natural enclosing covering (as a membrane or integument)

especially : a lipoprotein unit membrane that forms the outer layer of some virions and surrounds the viral capsid

These glycoprotein complexes, swept up by the budding virus as it acquires its envelope, are crucial to HIV's ability to infect new cells.

—William A. Haseltine et al., Scientific American