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

Once there, mtDNA fragments can make their way into the nucleus either through pores in its wall or, if the cell divides, seep in while the envelope dissolves and reassembles. —Martin Picard, Scientific American, 3 Jan. 2025

Once an envelope is empty, spending in that category stops, encouraging discipline and mindful decision-making. —True Tamplin, Forbes, 2 Jan. 2025

After Le Vau’s death, Hardouin-Mansart continued the envelope’s aesthetic, drawing inspiration from Renaissance-era Italian villas for his 1680s additions. —Morgan Goldberg, Architectural Digest, 30 Dec. 2024

In 2015, the night before flying back to New York from Barcelona, the performers were each handed a white envelope stuffed with $100 bills. —Michael Rothfeld, New York Times, 29 Dec. 2024

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

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