envelope

American  

[en-vuh-lohp, ahn-] / ˈɛn vəˌloʊp, ˈɑn- /

noun

envelopes plural

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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Other Word Forms

Noun Inflected Forms

• envelopes
  plural

Etymology

Origin of envelope

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

Explanation

An envelope is something that envelops, or wraps around. It usually refers to the thing you stick a stamp on and snail mail. In the early 1700s, envelope, the noun for "wrapper," evolved from the French enveloppe, meaning “to envelop.” Envelope is always a noun, unlike the verb envelop which means “to wrap, cloak.” Synonyms for envelope range from casing and enclosure to pouch and sheath. Virginia Woolf said, “Life is a luminous halo, a semi-transparent envelope surrounding us from the beginning.” She ditched hers by walking into a river with her pockets full of rocks.

Example Sentences

See Examples For:

envelope envelopes

The researchers say they still do not know exactly how APOE2 stabilizes the nuclear envelope and strengthens DNA repair.

From Science Daily ● Jul. 24, 2026

This is the movie inside the final red envelope.

From MarketWatch ● Jul. 18, 2026

This acts like an envelope and all the researchers need to do is change the letter inside before posting it into the body.

From BBC ● Jul. 13, 2026

When the reporter placed a letter for Paxton in the mailbox, an envelope addressed to Warren Paxton, the attorney general’s given name, was visible.

From Salon ● Jul. 7, 2026

He picked up the envelope and went over to sit on the floor with his back pressed against the door, so he’d have some warning if anyone tried to come in.

From "Found" by Margaret Peterson Haddix

"Covalently bonded carbon and hydrogen in comet and asteroid material are believed to have formed in the outer envelopes of stars, in high-energy events like supernovae, and in interstellar environments," Ms. Losurdo said.

From Science Daily ● Jul. 19, 2026

Using AI to examine signatures on ballot envelopes is a relatively new frontier, according to most experts consulted by ProPublica and the FBI tech specialist.

From Salon ● Jul. 17, 2026

That could mean setting up a direct debit from your current account to a savings account, organising cash into different envelopes or using round-up tools that put spare change aside when you spend.

From BBC ● Jul. 8, 2026

He said many counties have ordered outgoing and return ballot envelopes for the election to ensure envelopes for more than 23 million California voters are ready to use by the Oct.

From Los Angeles Times ● Jul. 2, 2026

I folded Jemma’s letters back into their envelopes and tucked them into my cigar box, but I could not stop my knees from bouncing as we rattled on down the tracks.

From "The Detective's Assistant" by Kate Hannigan

Related Words

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