Nucleus

"Nucleus" comes from the Latin for center or core. It can refer to several different concepts:

• In chemistry and physics, the term used to describe that collection of protons and neutrons in the center of an atom that carry the bulk of the atom's mass and positive charge. See atomic nucleus and nuclear physics.
• In cell biology, nucleus refers to the cell nucleus: a membrane-bound subcellular organelle found in eukaryotes, visible via microscopy, which contains, primarily, the cell's chromosomes.
• In neuroanatomy, a nucleus is a central nervous system structure that is composed mainly of gray matter and mediates electrical signaling within a particular subsystem.
• In astronomy, the solid core of a comet is referred to as the comet's nucleus.
• In astronomy, the central region of a galaxy is referred as the galaxy nucleus.
• In meteorology, an ice crystal is formed around an ice nucleus.
• In meteorology, the development of a cloud droplet is based on a cloud condensation nucleus.
• Nucleus: In linguistics, this is the center part of a syllable, most often a vowel.