See Also: nucleus(encyclopedia)
Nucleus(health)
Nucleus(medicine)
nucleus(dictionary)
red nucleus(medicine)
nucleus(dictionary)
roof nucleus(medicine)
nucleus acusticus(medicine)
nucleus intermediomedialis(medicine)
nucleus ambiguus(medicine)

nucleus (iou)



nucleus noun & verb. E18.
[Latin = nut, kernel, inner part, var. of nuculeus, formed as NUCULE.]
A. noun. Pl. -clei , -cleuses.
Astronomy.
a. The dense core of the head of a comet. E18.
b. A dense, usu. bright, central part in a galaxy or nebula. L18.
Each of a supposed series of concentric layers within the earth. Only in E18.
Botany. The kernel of a nut or seed; the nucellus of an ovule. Also, the hilum of a starch granule. Now rare. E18.
The central part or thing around which others are grouped or collected; the centre or kernel of an aggregate or mass; an initial part or collection of things to which others may be added. M18.
J. H. Bennet A very fair collection of modern books..as the nucleus of a library. Christian Aid News Those units were eventually to form the nucleus of the new Sudan People's Liberation Army. Jan Morris The tight, tough island quarter..the original nucleus of the city. attrib.: Westminster Gazette They will have nucleus crew of two-fifths of their war complement.
b. A small particle in a fluid on which crystals, droplets, or bubbles can form; a particle that initiates nucleation. M19.
c. A small colony of bees, including a queen, esp. as used to found a new colony. L19.
Anatomy. A discrete collection of neurones of similar type in the central nervous system. Chiefly with specifying word. E19.
caudate nucleus, lenticular nucleus, olivary nucleus, etc.
Archaeology. A stone from which flakes have been removed to make implements; a core. M19.
Biology. A cell organelle present in most living cells (though not those of bacteria), usu. as a single rounded structure bounded (except when undergoing division) by a double membrane within which lie the chromosomes, and functioning as a store of genetic information and as the director of metabolic and synthetic activity in the cell. Also occas., a nucleoid. Cf. EUKARYOTE, PROKARYOTE. M19.
Chemistry. A ring structure or other arrangement of atoms which is characteristic of a group of compounds. M19.
Physics. The positively charged central core of an atom, comprising most of its mass but occupying only a very small part of its volume and composed of protons and (usu.) neutrons. E20.
Linguistics.
a. The most prominent syllable or syllables in a word or utterance. E20.
b. The main or central word or words in a derivative, phrase, or sentence. M20.
b. verb trans. Make into or provide with a nucleus, concentrate (something). rare. E19.