shell

shell — noun

1. the hard natural outer layer that protects an egg, nut, seed, or an animal such

1.nounB2
Definition

the hard natural outer layer that protects an egg, nut, seed, or an animal such as a turtle, crab, or snail

Example

Liam cracked the egg shell and let the yolk drop into the bowl.

countable: a single egg shell

The turtle pulled its head inside its shell when the dog came near.

Common collocations
  • crack a shell
  • hard shell
  • remove the shell
  • inside a shell
Synonyms
  • covering

    more general; a shell is a specific type of hard covering

  • carapace

    technical term for the upper shell of a turtle or crustacean

Usage Note

Countable when referring to individual items (an eggshell, a snail shell); uncountable when referring to the material in general ('the shell of a nut is hard').

Common Mistakes

The turtle has a hard skin on its back.
The turtle has a hard shell on its back.
The hard protective covering of a turtle is called a shell, not skin.

2. the outer walls or frame of a building, vehicle, or other large structure, espec

2.nounB2
Definition

the outer walls or frame of a building, vehicle, or other large structure, especially when the inside parts are missing, destroyed, or not yet completed

Example

After the fire, only the shell of the school building remained standing.

shell of [a building]: empty outer structure after destruction

The construction crew finished the concrete shell before winter arrived.

Common collocations
  • shell of a building
  • empty shell
  • outer shell
  • concrete shell
Synonyms
  • framework

    emphasizes the supporting structure rather than the outer surface

  • hull

    specific to ships and boats

  • carcass

    used for the remains of a building or vehicle after destruction

Usage Note

Subject is often a building or vehicle that has been damaged, abandoned, or is under construction. Frequently used with 'just a shell' or 'only a shell' to emphasize emptiness.

3. a metal container packed with explosive material that a large gun shoots toward

3.nounB2
Definition

a metal container packed with explosive material that a large gun shoots toward a target, where it detonates on impact

Example

A shell exploded near the hospital, forcing everyone to take cover.

shell + explode: describes detonation of artillery

The old cannon fired a shell that landed over a kilometre away.

Common collocations
  • fire a shell
  • exploding shell
  • artillery shell
  • shell landed
Synonyms
  • projectile

    more general; refers to any object fired from a weapon

  • round

    a single unit of ammunition, including but not limited to shells

Common Mistakes

The soldier fired a shell from his handgun.
The soldier fired a shell from the cannon.
Shells are fired from large guns like cannons and howitzers, not from small handguns.

4. a long, very narrow, lightweight boat designed for racing, in which a team of pe

4.nounB2
Definition

a long, very narrow, lightweight boat designed for racing, in which a team of people sit in a line and pull oars

Example

The university rowing team practised in their new shell every morning.

Eight rowers climbed carefully into the shell so it would not tip over.

shell as a racing rowing boat

Common collocations
  • racing shell
  • rowing shell
  • eight-person shell
Synonyms
  • scull

    a light racing boat for one or two rowers, each using two oars

  • rowboat

    general term; a shell is a specialized type of rowboat

5. a business that exists only on official documents, with no real offices, employe

5.nounB2
Definition

a business that exists only on official documents, with no real offices, employees, or operations, often used to hide money, avoid taxes, or carry out illegal activities

Example

The police discovered that the money went through a shell company in Panama.

shell company: a fake business for hiding money

Gabriela registered a shell company to move funds between overseas accounts.

Common collocations
  • set up a shell company
  • shell company in
  • through a shell company
Synonyms
  • front company

    a legitimate-looking business used to conceal illegal activity

  • paper company

    emphasizes that the company exists only on paper

Usage Note

Frequently appears in news stories about financial crime and tax avoidance. Often followed by 'in [country/city]' to indicate where it was registered.

6. a small edible container made of pastry, chocolate, or other food material, hold

6.nounB2
Definition

a small edible container made of pastry, chocolate, or other food material, holding either a sweet or a salty filling inside

Example

For dessert, the chef filled chocolate shells with fresh raspberry cream.

chocolate shells: edible containers made of chocolate

The bakery sold tiny pastry shells stuffed with cheese and spinach.

Common collocations
  • pastry shell
  • chocolate shell
  • tart shell
  • filled shell
Synonyms
  • tartlet

    a small pastry shell, typically for desserts

  • casing

    more general; the outer layer that holds a filling

7. the outer behaviour or attitude that a person shows to others in order to hide t

7.nounB2
Definition

the outer behaviour or attitude that a person shows to others in order to hide their true feelings, especially when they are shy, hurt, or vulnerable

Example

Under his tough shell, Sahil is actually very kind and caring.

tough shell: a defensive outer personality

Allison built a shell around herself after her closest friend moved away.

Common collocations
  • out of one's shell
  • come out of one's shell
  • into one's shell
  • tough shell
  • protective shell
Synonyms
  • façade

    implies something deliberately false or misleading, not just protective

  • reserve

    a quieter, more neutral form of emotional distance

Antonyms
  • openness

    willingness to share true feelings

Usage Note

Common in fixed expressions: 'come out of your shell' (become more outgoing) and 'retreat into your shell' (become withdrawn). Often refers to a protective response to emotional pain.

Idioms

to become quieter and less willing to talk to people, often because of embarrassment, shyness, or emotional hurt

After being laughed at in class, Linh went into her shell and stopped raising her hand.

When strangers visit, the little boy goes into his shell and hides behind his mother.

to become more confident, sociable, and willing to join in conversations or activities

Élise used to be very shy, but she came out of her shell after joining the drama club.

The summer camp helped the quiet children come out of their shells and make new friends.

To stop being shy and start interacting more confidently with others.

After joining the drama club, Maya came out of her shell.

Did you see how Diego came out of his shell at the party?

To become quieter and avoid social interaction, often due to feeling uncomfortable.

When criticized, Brian retreated into his shell for days.

Why does Sara go into her shell whenever strangers visit?

shell — verb

Word family

  • shelled
    adjectiveB2
  • shell-less
    adjectiveC1
  • shellfish
    nounA2
  • shelling
    nounC1

Synonym discussion

Sense: noun/1

All four words refer to an outer layer that protects something. Shell is the most common learner word, used for eggs, nuts, turtles, and mollusks. Covering is much broader — any layer that covers something, from a thin cloth to a thick coat, qualifies. Carapace is a technical zoological term for the upper shell of a turtle, crab, or similar creature; learners at C2 level might encounter it in biology texts, but it sounds unnatural in everyday talk about cooking or pets. Crust refers specifically to a hard, brittle outer layer, most often of bread or the Earth's surface. For example, you crack a walnut shell but cut through a bread crust, and a scientist studies a turtle's carapace while a child collects pretty seashells on the beach — the right word depends on what is being covered and how hard the layer is.

Common collocations

Nouns

  • egg shell
  • nut shell
  • sea shell
  • turtle shell
  • artillery shell
  • racing shell
  • pastry shell

Phrases

Prepositions

  • inside a shell
  • out of one's shell
  • shell of a building

Etymology

Proto-GermanicOld EnglishMiddle EnglishEnglish

The English word 'shell' comes from Old English 'scell' (or 'scealu'), meaning a hard outer covering that naturally separates from the softer part inside. It is related to Old Norse 'skel' (shell) and Proto-Germanic '*skalō' (to split, separate), reflecting the idea of something that peels off or divides. The sense of an artillery projectile dates from the 1500s, referring to the metal 'shell' that held gunpowder. The figurative use for a person's protective emotional barrier appeared in the early 1800s.