Nucleus ¹

Definition: A kernel; hence, a central mass or point about which matter is gathered, or to which accretion is made; the central or material portion; used both literally and figuratively.

Nucleus ²

Definition: The body or the head of a comet.

Nucleus ³

Definition: An incipient ovule of soft cellular tissue.

Nucleus ⁴

Definition: A whole seed, as contained within the seed coats.

Nucleus ⁵

Definition: A body, usually spheroidal, in a cell or a protozoan, distinguished from the surrounding protoplasm by a difference in refrangibility and in behavior towards chemical reagents. It is more or less protoplasmic, and consists of a clear fluid (achromatin) through which extends a network of fibers (chromatin) in which may be suspended a second rounded body, the nucleolus (see Nucleoplasm). See Cell division, under Division.

Nucleus ⁶

Definition: The tip, or earliest part, of a univalve or bivalve shell.

Nucleus ⁷

Definition: The central part around which additional growths are added, as of an operculum.

Nucleus ⁸

Definition: A visceral mass, containing the stomach and other organs, in Tunicata and some mollusks.

nucleus ⁹

Definition: a part of the cell containing DNA and RNA and responsible for growth and reproduction

nucleus ¹⁰

Definition: any histologically identifiable mass of neural cell bodies in the brain or spinal cord

nucleus ¹¹

Definition: a small group of indispensable persons or things; "five periodicals make up the core of their publishing program"

nucleus ¹²

Definition: the positively charged dense center of an atom

nucleus ¹³

Definition: (astronomy) the center of the head of a comet; consists of small solid particles of ice and frozen gas that vaporizes on approaching the sun to form the coma and tail