A weapon that derives its energy from the nuclear reactions of either fission or fusion.
The massive, positively charged central part of an atom, made up of protons and neutrons.
A large membrane-enclosed organelle found in eukaryotic cells which contains genetic material.
The central part of a syllable, most commonly a vowel.
The core, central part of something, around which other elements are assembled.
An initial part or version that will receive additions.
A ganglion, cluster of many neuronal bodies where synapsing occurs.