nucleus

The word “nucleus” means the central, positively charged part of an atom, made of protons and neutrons. In plain terms, the central core of something — whether an atom, a cell, or a group.

“Nucleus” is pronounced NYOO-klee-uhs (/ˈnuː.kli.əs/ in IPA).

Here is “nucleus” used in a sentence: “Electrons orbit the nucleus of an atom.”

“Nucleus” is a noun.

The word “nucleus” comes from Latin. A learned borrowing from Latin nucleus, "kernel" or "core.".

“Nucleus” is an uncommon word in modern English, usually learned at around the B1 level.

“Nucleus” has 3 distinct senses listed in this dictionary. The most common is: the central, positively charged part of an atom, made of protons and neutrons.

The nucleus of an atom is the central, positively charged core made of protons and neutrons, and it is the seat of an atom's mass and charge. The nucleus of a cell is a completely different structure: a membrane-bound compartment that holds the cell's genetic material. The two share only the name, referring to a central core in very different scientific contexts.

Yes, nucleus is often used figuratively to describe the core part of something around which everything else is built, such as 'the nucleus of a new team' or 'the nucleus of an idea.' In this sense it means the central, foundational element rather than anything biological or physical.

The traditional plural is nuclei, following the word's Latin origin, though nucleuses is also used informally in English. Nuclei remains the standard form in scientific and academic writing.