Definition of nucleus :
1. 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.
2. 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.
3. A visceral mass, containing the stomach and other organs, in Tunicata and some mollusks.
4. A whole seed, as contained within the seed coats.
5. An incipient ovule of soft cellular tissue.
6. The body or the head of a comet.
7. The central part around which additional growths are added, as of an operculum.
8. The tip, or earliest part, of a univalve or bivalve shell.
nitty-gritty, core group, premise, substance, burden, matter, basis, pith, inwardness, heart and soul, germ, bud, cell nucleus, start, effect, lens nucleus, sum, magnetic core, karyon, spark, embryo, gist, centre, foundation
centrality (part of speech: noun)
middle (part of speech: noun)
focus (part of speech: noun)
focus, magnet, hub, asymptote, epitome, kernel, core, gathering, essence, intersection, meat, funnel, polestar, marrow, bottleneck, lodestar, forum, lure, axle, soul, rendezvous, plenum, spirit, heart, crossing, center, crux, rally
- Deep Willows was the nucleus about which he had hoped to build his edifice.
- There is a need to- day of a new form of existence for Christianity; but the satisfaction of this need will not grant us the spiritual nucleus itself. - "An Interpretation of Rudolf Eucken's Philosophy", W. Tudor Jones.
- When the general offices of the Chicago and Northwestern Railroad were removed to Chicago in 1865, Mr. Leonard moved the fine job office connected with the " Herald" to that city, as the nucleus for the extensive printing establishment he later acquired. - "Famous Prima Donnas", Lewis Clinton Strang.