nucleolus

noun nu·cle·o·lus \ nü-ˈklē-ə-ləs , nyü- \

|Updated on: 3 Jun 2018

Definition of nucleolus

plural nucleoli play \nü-ˈklē-ə-ˌlī, nyü-\

: a spherical body of the nucleus of most eukaryotes that becomes enlarged during protein synthesis, is associated with a nucleolus organizer, and contains the DNA templates for ribosomal RNA — see cell illustration

—

nucleolar

play \nü-ˈklē-ə-lər, nyü-\ adjective

See nucleolus defined for kids

Recent Examples of nucleolus from the Web

But there’s more to the nucleolus than just making ribosomes.

— joanna klein, New York Times, "The Thing Inside Your Cells That Might Determine How Long You Live," 20 May 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'nucleolus.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

Origin and Etymology of nucleolus

New Latin, from Latin, diminutive of nucleus

NEW! Time Traveler

First Known Use: 1839

in the meaning defined above

See Words from the same year

Medical Dictionary

nucleolus

noun nu·cle·o·lus \ n(y)ü-ˈklē-ə-ləs \

medical Definition of nucleolus

plural nucleoli play \-ˌlī\

: a spherical body of the nucleus of most eukaryotes that becomes enlarged during protein synthesis, is associated with a nucleolus organizer, and contains the DNA templates for ribosomal RNA — called also plasmosome

Illustration of nucleolus

Learn More about nucleolus

Britannica.com: Encyclopedia article about nucleolus

Seen and Heard

What made you want to look up nucleolus? Please tell us where you read or heard it (including the quote, if possible).

show

WORD OF THE DAY

notorious

play

widely and unfavorably known

BROWSE DICTIONARY

nucleolocentrosome

nucleoloid

nucleolus

nucleolus organizer

nucleolysis

Test Your Vocabulary

Words for Summer: A Quiz

Which of the following words means “of or relating to summer”?

Name That Thing

Test your visual vocabulary with our 10-question challenge!

TAKE THE QUIZ

Word Winder's CrossWinder

Test Your Knowledge - and learn some interesting things along the way.

TAKE THE QUIZ

Words at Play

Ask the Editors

Word Games