Nucleus

Nucleus may refer to:
 * Nucleus (atomic structure), the very dense region at the center of an atom
 * Cell nucleus, the control center of a cell, which contains the cell's chromosomal DNA
 * Nucleus (neuroanatomy), a cluster of neurons in the central nervous system
 * Nucleus (syllable), the central part of a syllable in linguistics
 * Comet nucleus, the solid, central part of a comet

Computer systems

 * Nucleus CMS, a weblog system
 * Nucleus RTOS, an operating system
 * Nucleus, a pioneering facility for the GEC 4000 series

Other uses

 * Nucleus (advocacy group), a UK-European political advocacy campaign organisation
 * Nucleus (band), a British jazz-rock band led by Ian Carr
 * Nucleus (video game), a 2007 downloadable game on the PlayStation Store
 * Nucleus (Anekdoten album), 1995
 * Nucleus (Sonny Rollins album), 1975
 * Nucleus Limited, an Australian medical research company, taken over by Pacific Dunlop in 1988
 * Nucleus, predecessor to Canadian rock band A Foot in Coldwater