shell

Pluralshells

Formsshells, shelling, shelled

1. 1
   nouncountable

   The hard protective outer covering of certain animals, such as mollusks, crustaceans, turtles, and beetles, or of an egg, nut, or seed.

   The hermit crab outgrew its old shell and searched for a larger one.

   Mollusk shells are built up gradually in thin layers of calcium carbonate.

   Note

   The plural belongs to the shoreline and to poetry: Tennyson, in In Memoriam (1850), pictures drowned hands that "toss with tangle and with shells." Not every shell is outside the animal, though. The cuttlefish carries its shell hidden under the mantle. Source

   Checked 2 Nov 2026 · 3 facts

   • Tennyson wrote In Memoriam, first published in 1850. en.wikisource.org
   • In Canto X, Tennyson imagines the dead man's hands tossing among seaweed and shells; the quoted wording is exact. en.wikisource.org
   • A cuttlefish has an internal shell beneath its mantle. en.wikipedia.org
2. 2
   nounfigurativelycountable

   The outer covering, casing, or framework of an object or structure, considered apart from its contents or interior, as with the bare frame of a building.

   The car's sleek shell hides a fairly ordinary engine.

   Designers preserved the historic shell of the theater and gutted the interior.

   Similarcasing, body, exterior, frame, framework

   Oppositeinterior, core

3. 3
   attack with gunsverbtransitive

   To bombard a target by firing projectiles at it, especially with artillery.

   Artillery units shelled the bridge to stop the advance.

   Warships began to shell the coastal defenses at first light.

   Similarbombard, pound, blast

   Note

   The verb of artillery takes its sense from the explosive projectile: to shell a place is to put shells into it. Joseph Conrad turns it to grim irony in Heart of Darkness (1899), where a warship is shelling the bush and "there wasn't even a shed there." Source

   Checked 2 Nov 2026 · 3 facts

   • The artillery verb shell derives its meaning from the projectile noun. web.stanford.edu
   • Joseph Conrad wrote Heart of Darkness, first published in 1899. en.wikisource.org
   • The story depicts a warship shelling the bush; the quotation is exact and occurs in Marlow's narration. gutenberg.org
4. 4
   pay outverbcolloquialtransitive

   To hand over or pay out money, often reluctantly.

   Fans shelled out hundreds of dollars for front-row seats.

   You'll have to shell out a lot to fix a roof that old.

   UsageUsually shell out money, often for something: we shelled out fifty dollars for parking.

   Similarpay, spend

5. 5
   nouncountable

   An explosive projectile, or its metal casing, fired from a large gun such as a cannon, howitzer, or mortar.

   The mortar shell whistled overhead before bursting in the open field.

   Each shell was timed to detonate above the enemy trenches.

   Similarround, projectile

   Note

   The siege-mortar shell is the word's most literal military use: a hollow casing packed with powder instead of a kernel. It burst by a fuse or on impact. Before shell became the usual name, the same projectile was called a bomb. A reader of older accounts of sieges may therefore meet bombs where a modern writer would say shells. Source

   Checked 1 Nov 2026 · 4 facts

   • Historical mortar shells were hollow casings filled with gunpowder. gutenberg.org
   • Explosive shells could use time-delayed or impact-triggered fuzes. en.wikipedia.org
   • Bomb was an earlier usual name for the projectile subsequently generally called a shell. gutenberg.org
   • Older siege accounts use bombs for mortar projectiles. nps.gov
6. 6
   gun cartridgenouncountable

   The cartridge or round of ammunition for a breechloading firearm.

   She slid a shell into the chamber and took aim.

   The hunter's pockets were full of spent shells.

   Similarcartridge, round, casing

   Note

   Among shooters and hunters, shell names the whole cartridge, from case and primer to propellant and shot, and it stretches loosely to cover load, bullet or round. The same word also covers what is left after firing. A spent shell is the empty case, so a pocketful of shells may be ammunition or litter depending on the adjective. Source

   Checked 1 Nov 2026 · 2 facts

   • A complete shotgun shell contains a case, primer, propellant and shot. nrawomen.com
   • Spent shells are the empty cases remaining after firing. nrawomen.com
7. 7
   remove coveringverbtransitive

   To strip something of its shell or other outer casing.

   She shelled a whole bowl of fresh peas for dinner.

   Workers shell the nuts by machine at the processing plant.

   UsageUsed for nuts, peas, shrimp and eggs; for fruit and vegetables with a skin, the verb is usually peel.

   Similarshuck, hull, husk, peel

8. 8
   emotional wallnouncountable

   A self-protective barrier that keeps a person from interacting with others.

   After the divorce, he retreated into a shell and rarely went out.

   A patient teacher can gently coax a shy child out of their shell.

   UsageMostly in set phrases: come out of your shell, retreat into your shell, bring someone out of their shell.

   Similarcocoon

9. 9
   empty remainsnounfigurativelycountable

   The empty outward form that remains when the substance or vitality inside has gone.

   Months of grief had reduced her to a hollow shell.

   Once a thriving business, the firm became an empty shell of its former self.

   UsageCommon in an empty shell, a mere shell and a shell of one's former self.

   Similarhusk, shadow

   Note

   Railway Magazine of April 1953 says the locomotive Kingsley was "little more than a shell" by the time it was scrapped, worn out by rough usage. Source

   Checked 2 Nov 2026 · 1 fact

   • The April 1953 Railway Magazine describes the locomotive Kingsley as "little more than a shell" when scrapped and attributes its condition to rough usage. Wiktionary identifies the source as "Notes and News: Locomotive Notes", page 283. en.wiktionary.org
10. 10
    command programnouncountable

    An operating-system interface whose main purpose is to launch other programs and interpret the user's commands.

    Most Linux users interact with the system through a shell such as Bash.

    He wrote a short script to automate the task from his shell.

    Note

    The image fits the software: the shell is the outer layer around the kernel, the part the user touches, and the internals can change while the shell stays the same. Shells are named like products. Stephen Bourne designed the Bourne shell for Unix, and Bash, the "Bourne-again shell," puns on being born again. Programmers also use shell as a verb, for switching to a command line. Source

    Checked 1 Nov 2026 · 4 facts

    • The shell provides the user's interface to the operating system and mediates interaction with the kernel. fsl.fmrib.ox.ac.uk
    • A shell can remain available across changes in the underlying operating system; Bash's portability supplies an example. tiswww.case.edu
    • Stephen Bourne designed the Bourne shell for Unix. archive.computerhistory.org
    • Bash expands to "Bourne-Again SHell", punning on Bourne's name and the expression "born again". tiswww.cwru.edu
11. 11
    front companynouncountable

    A legal entity that exists in name but carries on no real business operations.

    The firm turned out to be a shell used to move money across borders.

    They acquired a dormant shell and used it to list on the stock exchange.

    UsageOften used before another noun: shell company, shell corporation.

    Similarfront

    Note

    A shell may be formed to acquire a single asset, such as an old factory, or kept as a vehicle for raising finance, holding assets or arranging mergers. A dormant shell can even be bought as a route onto a stock exchange. Because the entity has a name but no operations, the word can also hint at concealment. Source

    Checked 2 Nov 2026 · 4 facts

    • A shell may be formed to acquire or hold a single asset, including property. fatf-gafi.org
    • Shell companies can serve as vehicles for raising finance. en.wikipedia.org
    • Shell companies can hold assets and facilitate mergers. fincen.gov
    • Acquiring control of a public shell through a reverse merger can provide a route to stock-exchange listing. sec.gov
12. 12
    electron layernouncountable

    In an atom, the group of orbitals that all have one particular principal quantum number.

    Electrons fill the innermost shell before occupying higher ones.

    Sodium has a single electron in its outermost shell.

    Note

    Chemists number the shells outward from the nucleus by the principal quantum number n. The nth shell can hold at most 2n² electrons, spread across its subshells. Electrons broadly fill inner shells before outer ones, though an outer shell can start before an inner one is full, so outermost shell is the phrase to know. Sodium, for example, carries a single electron in its outermost shell. Source

    Checked 1 Nov 2026 · 5 facts

    • Shells are numbered outward from the nucleus using the principal quantum number n. en.wikipedia.org
    • The maximum electron capacity of the nth shell is 2n². en.wikipedia.org
    • Electron shells contain subshells. learninglab.rmit.edu.au
    • Electrons occupy subshells in order of increasing energy; an outer shell can begin filling before an inner shell is complete. For example, 4s fills before 3d. learninglab.rmit.edu.au
    • A neutral sodium atom in its ground state has one electron in its outermost shell. physics.nist.gov

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