D defs.my
Entry 5 senses Webster, 1913

Nucleus

/no͞ok'-lē-əs/ · Nu·cle·us · IPA /ˈnuː.kli.əs/
01 n. A kernel; hence, a central mass or point about which matter is gathered, or to which accretion is made; the central or material portion; --…
pl. Nucleuses, Nuclei ((#))
  1. 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.
    “It must contain within itself a nucleus of truth.” I. Taylor.
  2. 2.
    The body or the head of a comet.(Astron.)
  3. 3.
    An incipient ovule of soft cellular tissue.(Bot.)
  4. 4.
    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 Cell division, under Division.(Biol.) See: Nucleoplasm, Division
  5. 5.
    The tip, or earliest part, of a univalve or bivalve shell.(Zool.)