Nuclei

How to spell nuclei

6 letters · 3 syllables

How to pronounce nuclei

Say the part in capitals loudest.

What does nuclei mean?

1. nounThe plural of nucleus: the central cores of atoms, cells, or other systems.

Nuclei in a sentence

• The atomic nuclei in the sample emitted measurable radiation.

• Under the microscope the stained nuclei of the cells were clearly visible.

Where does nuclei come from?

Language of origin: Latin

This is the plural of nucleus, which comes directly from the Latin word nucleus meaning 'kernel' or 'little nut'. That noun was a diminutive of nux, the Latin for 'nut', so the original picture was of the small core hidden inside a shell. Scientists of the eighteenth and nineteenth centuries borrowed the Latin word wholesale to name the central core of a thing, first in botany and biology for the dense body inside a living cell, and later in physics for the dense centre of an atom. Because the word kept its Latin form, it also kept the Latin plural: a second-declension noun ending in -us forms its plural in -i, giving nuclei rather than an English '-uses'. That inherited Latin ending is exactly the spelling trap, since the singular ends in -eus but the plural swaps to -ei.

How the word is built

• nucle- (from Latin nucleus: kernel, little nut)
• -i (Latin masculine plural ending)