nucleus
gb/nˈukliəs/ us/nˈukliəs/
B2
English
~ 6500
mag, sejtmag, atommag, üstökösmag, alapváz, molekulaváz
NOUN
B2
1
mag
B1
Usage pattern:
the nucleus of [something]
A small group of volunteers formed the nucleus of the new charity.
Önkéntesek egy kis csoportja alkotta az új jótékonysági szervezet magját.
The city’s tech district is the nucleus of its innovation economy.
A város technológiai negyede az innovációs gazdaságának magja.
At that time, there was only a tiny nucleus of dedicated fans, but the band soon became famous.
These early chapters contain the nucleus of the ideas that shaped his later work.
Family and close friends are often the nucleus of a person’s support network.
Learner examples
A few students formed the nucleus of the English club.
Néhány diák alkotta az angolklub magját.
Trust is the nucleus of a good relationship.
A bizalom a jó kapcsolat alapja.
This small town became the nucleus of the country’s oil industry.
Her first book was the nucleus of her long writing career.
Common mistake:
Learners sometimes confuse "nucleus" with more common words like "core" or "center". In general English, "core" and "center" are more frequent, and "nucleus" can sound more formal or technical. Another common issue is the plural form: the usual plural is "nuclei" /ˈnuːkliˌaɪ/ or /ˈnjuːkliˌaɪ/, not *"nucleuses" in most written English, although "nucleuses" is sometimes accepted in general contexts.
Meaning
central or most important part
Collocations
the nucleus of the group
|form the nucleus of
|nucleus of a movement
|nucleus of an idea
|nucleus of a team
|small nucleus of supporters
Synonyms
core (The most common everyday word for the central or most important part of something; slightly broader and less formal than "nucleus".)
|
hub (Suggests a busy, active center of activity, while "nucleus" can be quieter or more abstract.)
Antonyms
periphery (Refers to the outer edge or less important parts, in contrast to "nucleus" as the central, important part.)
|
fringe (Describes people or things at the edge of a group or activity, opposite of the central "nucleus".)
Themes
general
|society
|abstract_ideas
|core_vocabulary
|education
Definition
The main part or small main group in the center of something that everything else grows around or depends on.
The central or most important part or small group around which the rest of something is built, organized, or develops.
NOUN
C1
TECHNICAL
2
sejtmag
B2
Usage pattern:
the nucleus of [a cell]
In eukaryotic cells, the DNA is stored inside the nucleus.
Az eukarióta sejtekben a DNS a sejtmagban tárolódik.
The nucleus is surrounded by a double membrane that separates it from the cytoplasm.
A sejtmagot kettős membrán veszi körül, amely elválasztja a citoplazmától.
Mutations in the proteins that move into and out of the nucleus can cause serious diseases.
Under the microscope, the stained nucleus appears darker than the rest of the cell.
The nucleus plays a key role in controlling cell growth and division.
Learner examples
The nucleus is in the center of the cell.
A sejtmag a sejt közepén van.
DNA is kept safe inside the nucleus.
A DNS a sejtmagban van védve.
The nucleus tells the cell what to do.
In many pictures of cells, the nucleus is shown as a dark circle.
Common mistake:
Learners often confuse the cell "nucleus" with the "nucleus" of an atom because they share the same word and both are in the center. In biology, the nucleus is a structure inside a cell, not inside an atom. Another common mistake is using only the adjective "nuclear" (as in "nuclear DNA") and forgetting that the noun for the cell structure is "nucleus".
Meaning
central part of a cell
Collocations
cell nucleus
|the nucleus of a cell
|within the nucleus
|inside the nucleus
|nuclear membrane surrounding the nucleus
|nucleus and cytoplasm
Synonyms
cell core (A descriptive phrase sometimes used informally in explanations; it is not a standard technical term like "nucleus".)
Antonyms
cytoplasm (Refers to the material of the cell outside the nucleus, contrasting with the central nucleus.)
Themes
science
|biology
|medicine
|health
|education
Definition
The main round part inside a cell that holds the cell’s DNA and controls what the cell does.
The membrane-bound central structure in most eukaryotic cells that contains the genetic material (DNA) and controls the cell’s activities.
C1
TECHNICAL
3
atommag
B2
Usage pattern:
the nucleus of [an atom]
Electrons move around the atomic nucleus in specific energy levels.
Az elektronok meghatározott energiaszinteken mozognak az atommag körül.
The number of protons in the nucleus determines which element an atom belongs to.
Az atommagban lévő protonok száma határozza meg, hogy az atom melyik elemhez tartozik.
In nuclear fission, the nucleus of an atom splits into smaller parts and releases energy.
Most of the mass of an atom is concentrated in its nucleus.
The nucleus is held together by the strong nuclear force.
Learner examples
The nucleus is at the center of the atom.
Az atommag az atom középpontjában van.
Protons and neutrons are in the nucleus.
A protonok és a neutronok az atommagban vannak.
Almost all the mass of the atom is in the nucleus.
Electrons move around the nucleus.
Common mistake:
Learners sometimes mix up the atomic nucleus with the cell nucleus because both are called "nucleus" and are central. In physics and chemistry, "nucleus" always refers to the center of the atom, not to a part of a cell. Another issue is confusing the pronunciation of "nucleus" /ˈnuːkliəs/ with the adjective "nuclear" /ˈnuːkliər/.
Meaning
central part of an atom
Collocations
atomic nucleus
|the nucleus of an atom
|split the nucleus
|nucleus and electrons
|nuclear charge of the nucleus
|unstable nucleus
Synonyms
atomic core (A descriptive phrase used in explanations; less precise and far less common than the technical term "nucleus".)
Antonyms
electron cloud (Refers to the region around the nucleus where electrons are found, contrasting with the central nucleus itself.)
Themes
science
|physics
|education
|core_vocabulary
Definition
The tiny, heavy center of an atom that is made of protons and neutrons and has a positive charge.
The dense central region of an atom, made up of protons and neutrons, that contains almost all of the atom’s mass and has a positive charge.
NOUN
C2
TECHNICAL
4
üstökösmag
C1
Usage pattern:
the nucleus of [a comet]
As the comet nears the sun, gas and dust stream away from its nucleus to form a bright tail.
Ahogy az üstökös közeledik a Naphoz, gáz és por áramlik ki a magjából, és fényes csóvát alkot.
Spacecraft images revealed that the comet’s nucleus is smaller and darker than scientists expected.
Az űrszondák felvételei megmutatták, hogy az üstökös magja kisebb és sötétebb, mint ahogy a tudósok várták.
The icy nucleus slowly evaporates when heated, feeding the surrounding coma.
Impacts on the nucleus can change the comet’s rotation and shape.
Learner examples
The nucleus of the comet is made of ice and dust.
Az üstökös magja jégből és porból áll.
When the comet gets hot, gas comes off the nucleus.
Amikor az üstökös felmelegszik, gáz szabadul fel a magjából.
Scientists sent a probe to study the nucleus of a comet.
Common mistake:
Learners may assume "nucleus" in space contexts refers to an atom or a cell. In astronomy, it usually refers specifically to the solid central part of a comet, not to atomic structure or biology.
Meaning
solid core of a comet
Collocations
comet nucleus
|the nucleus of the comet
|icy nucleus
|active nucleus
|dark nucleus
|nucleus and coma
Synonyms
core (A general word for the central part of something; less precise than the technical term "nucleus" in astronomy.)
Antonyms
comet tail (Refers to the extended, outer part of a comet, contrasting with the small central nucleus.)
Themes
science
|space
|astronomy
|education
Definition
The hard center of a comet, mostly ice and dust, that makes the bright cloud and tail when it gets close to the sun.
The solid central part of a comet, made mainly of ice and dust, from which the coma and tail develop when the comet approaches the sun.
NOUN
C2
TECHNICAL
5
alapváz
C1
molekulaváz
C1
Usage pattern:
the nucleus of [a molecule/structure]
The benzene nucleus is a common structural feature in many organic compounds.
A benzolgyűrű sok szerves vegyületben gyakori szerkezeti elem.
In this drug molecule, several side chains are attached to a steroid nucleus.
Ebben a gyógyszermolekulában több oldallánc kapcsolódik egy szteroidvázhoz.
Substitutions on the aromatic nucleus can greatly change a compound’s reactivity.
Learner examples
Many molecules have a main nucleus with small groups on it.
Sok molekulának van egy fő alapváza, amelyhez kisebb csoportok kapcsolódnak.
The benzene nucleus is a ring of six carbon atoms.
A benzolgyűrű hat szénatomból álló gyűrű.
Chemists look at the nucleus of the molecule and the groups attached to it.
Common mistake:
This sense is quite technical, and learners may confuse it with the atomic nucleus. In chemistry, here "nucleus" refers to the central arrangement of atoms in a molecule, not the center of a single atom.
Meaning
central part of a molecule
Collocations
benzene nucleus
|aromatic nucleus
|nucleus of the molecule
|steroid nucleus
|ring nucleus
Synonyms
ring (Refers specifically to cyclic structures; overlaps with some uses of "nucleus" but is more concrete and structural.)
Antonyms
substituent (A group attached to a central structure; it contrasts with the central "nucleus" of the molecule.)
Themes
science
|chemistry
|education
Definition
In chemistry, the main central part of a molecule, often a ring of atoms, that other parts are joined to.
In chemistry, the central part of a molecule or structure, often a characteristic ring or group of atoms, to which other atoms or groups are attached.
Grammar
Dictionary form
nucleus
IPA
GB/nˈukliəs/
US/nˈukliəs/
Syllables & stress
nuc - le - us (3 syllables)
Stress on 1st syllable (nuc)
Word forms
Noun
- Base: nucleus
- Plural: nuclei, nucleuses
Word family
Forms
nuclei
noun
nucleuses
noun
Core family
nuclear
adjective B1
Negative and opposite forms
non-nuclear
adjective
antinuclear
adjective
Advanced or less common
nucleic
adjective
nucleate
verb
nucleation
noun
Expressions
cell nucleus
1/sˈɛl nˈukliəs/
fixed phrase
technical
central DNA-containing part of a cell
the part in the center of a cell that holds the cell’s DNA
Examples
- The cell nucleus is clearly visible under the microscope.
- Damage to the cell nucleus can stop the cell from dividing correctly.
form the nucleus of
1/fˈɔɹm ðə nˈukliəs əv/
fixed phrase
be the central core of something
to be the small main group or part at the center of something, especially at the beginning, that the rest grows around
Examples
- These early supporters will form the nucleus of the new organization.
- A handful of experienced players formed the nucleus of the national team.
- The pilot project formed the nucleus of a much larger education program.
atomic nucleus
1/ətˈɑmɪk nˈukliəs/
fixed phrase
technical
central core of an atom
The tiny center of an atom that holds protons and neutrons.
Examples
- Most of an atom’s mass is in the atomic nucleus.
- The atomic nucleus carries a positive charge because of the protons.
- Electrons move around the atomic nucleus in different energy levels.
- Nuclear power plants use energy released from changes in the atomic nucleus.
- The discovery of the atomic nucleus changed ideas about matter.