noun

• The core, central part of something, around which other elements are assembled.
• An initial part or version that will receive additions.
• (chemistry, physics) The massive, positively charged central part of an atom, made up of protons and neutrons.
• (cytology) A large membrane-enclosed organelle found in eukaryotic cells which contains genetic material.
• (neuroanatomy) A ganglion, cluster of many neuronal bodies where synapsing occurs.
• (phonetics, phonology) The central part of a syllable, most commonly a vowel.