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

Others argued the study’s coarse global filters undercount capacity that regional geological surveys already include, or that emerging pathways (like mineralization) could widen the envelope. —Phil De Luna, Forbes.com, 9 Sep. 2025

Katie meets with Jenn, her last hope for a friend on the show, with a manila envelope inside of which she’s printed out several pages from a website that employs Wendie, the polygraph tech with a Bettie Page haircut. —Peter Larsen, Oc Register, 5 Sep. 2025

Nonetheless, many states have implemented additional safeguards around mail-in ballots, such as video monitoring on ballot drop boxes, limiting the number or hours that drop boxes that can be left outside and requiring voters to provide their identification numbers on their ballot envelopes. —Carlie Procell, USA Today, 2 Sep. 2025

Both cards are in envelopes devoid of any postage markings or stamps, which suggests they were sent as part of a larger package. —Chris Spargo, People.com, 2 Sep. 2025

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