Cell nucleus, the control center of a cell, which contains the cell's chromosomal DNA

Galaxy nucleus, the central region of a galaxy.

Atomic nucleus, the collection of protons and neutrons in the center of an atom, also composed of subatomic matter

Nucleic acid

Nucleation is the onset of a phase transition in a small region. The phase transition can be the formation of a bubble or of a crystal from a liquid. Creation of liquid droplets in saturated vapor or the creation of gaseous bubble in a saturated liquid...

In cell biology, the nucleolus (plural nucleoli) is a sub-organelle of the cell nucleus, which itself is an organelle. A main function of the nucleolus is the production and assembly of ribosome components. The nucleolus is roughly spherical, and is...

Cloud condensation nuclei, the basis for the development of a cloud droplet

Nucleus CMS, an open-source weblog system

Nucleus RTOS, a brand of operating system

Comet nucleus, the solid core of a comet.

Nucleus (band), a British jazz-rock band led by Ian Carr

Syllable nucleus, the central part of a syllable

Ice nucleus, the center of an ice crystal

Nucleus (neuroanatomy), a central nervous system structure composed mainly of gray matter

Sentence nucleus, the syllable which receives the greatest stress in a word

Nucleus (video game), a downloadable game on the PlayStation Store