Source: The Collaborative International Dictionary of English v.0.48
Nucleus \Nu"cle*us\, n.; pl. E. Nucleuses, L. Nuclei. [L., a
kernel, dim. fr. nux, nucis, nut. Cf. Newel post.]
[1913 Webster]
1. 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.
[1913 Webster]
It must contain within itself a nucleus of truth.
--I. Taylor.
[1913 Webster]
2. (Astron.) The body or the head of a comet.
[1913 Webster]
3. (Bot.)
(a) An incipient ovule of soft cellular tissue.
(b) A whole seed, as contained within the seed coats.
[1913 Webster]
4. (Biol.) A body, usually spheroidal, in a eukaryotic cell,
distinguished from the surrounding protoplasm by a
difference in refrangibility and in behavior towards
chemical reagents, which contains the chromosomal genetic
material, including the chromosomal DNA. 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 Celldivision, under Division.
[1913 Webster +PJC]
Note: The nucleus is sometimes termed the endoplast or
endoblast, and in the protozoa is supposed to be
concerned in the female part of the reproductive
process. See Karyokinesis.
[1913 Webster]
5. (Zool.)
(a) The tip, or earliest part, of a univalve or bivalve
shell.
(b) The central part around which additional growths are
added, as of an operculum.
(c) A visceral mass, containing the stomach and other
organs, in Tunicata and some mollusks.
[1913 Webster]
nucleus
n 1: a part of the cell containing DNA and RNA and responsible
for growth and reproduction [syn: cell nucleus, karyon]
2: the positively charged dense center of an atom
3: a small group of indispensable persons or things; "five
periodicals make up the core of their publishing program"
[syn: core, core group]
4: (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
5: any histologically identifiable mass of neural cell bodies
in the brain or spinal cord
[also: nuclei (pl)]