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fission

 - 5 dictionary results

fis⋅sion

  [fish-uhn]
Use fission in a Sentence
–noun
1. the act of cleaving or splitting into parts.
2. Also called nuclear fission. Physics. the splitting of the nucleus of an atom into nuclei of lighter atoms, accompanied by the release of energy. Compare fusion (def. 4).
3. Biology. the division of an organism into new organisms as a process of reproduction.
–verb (used without object)
4. Physics. to undergo fission.
–verb (used with object)
5. Physics. to cause to undergo fission.
Origin:
1835–45; < L fissiōn- (s. of fissiō) a splitting, dividing, equiv. to fiss(us) divided (see fissi- ) + -iōn- -ion
Dictionary.com Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2009.
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fis·sion   (fĭsh'ən)   


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n.  

  1. The act or process of splitting into parts.

  2. A nuclear reaction in which an atomic nucleus, especially a heavy nucleus such as an isotope of uranium, splits into fragments, usually two fragments of comparable mass, releasing from 100 million to several hundred million electron volts of energy.

  3. Biology An asexual reproductive process in which a unicellular organism divides into two or more independently maturing daughter cells.

v.   fis·sioned, fis·sion·ing, fis·sions

v.   tr.
To cause (an atom) to undergo fission.
v.   intr.
To undergo fission.

[Latin fissiō, fissiōn-, a cleaving, from fissus, split; see fissi-.]
The American Heritage® Dictionary of the English Language, Fourth Edition
Copyright © 2009 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.
Cite This Source
Medical Dictionary

Main Entry: fis·sion
Pronunciation: 'fish-&n also 'fizh-
Function: noun
1 : a method of reproduction in which a living cell or bodydivides into two or more parts each of which grows into a whole new individual
2 a : CLEAVAGE 2 b : the splitting of an atomic nucleus resulting in the release of large amounts of energy called also nuclear fission —fis·sion verb fis·sioned; fis·sion·ing /'fish-(&-)ni[ng] also 'fizh-/
—fis·sion·al /'fish-&n-&lalso 'fizh-/ adjective
Merriam-Webster's Medical Dictionary, © 2002 Merriam-Webster, Inc.
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Medical Dictionary

fission fis·sion (fĭsh'ən)
n.

  1. The act or process of splitting into parts.

  2. The amitotic division of a cell or its nucleus.

  3. An asexual process of reproduction in which a unicellular organism divides into two or more independently maturing daughter cells.

  4. A nuclear reaction in which an atomic nucleus, especially a heavy nucleus such as an isotope of uranium, splits into fragments, usually two of comparable mass, with the evolution of from 100 million to several hundred million electron volts of energy.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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Science Dictionary
fission   (fĭsh'ən)  Pronunciation Key 


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  1. The splitting of an unstable atomic nucleus into two or more nuclei. Fission occurs spontaneously, generally when a nucleus has an excess of neutrons, resulting in the inability of the strong force to bind the protons and neutrons together. The fission reaction used in many nuclear reactors and bombs involves the absorption of neutrons by uranium-235 nuclei, which immediately undergo fission, releasing energy and fast neutrons. Compare fusion.

  2. A process of asexual reproduction in which a single cell splits to form two identical, independent cells. In fission, the chromosomal DNA replicates before the cell divides. Most bacteria and other prokaryotes reproduce by means of fission. Also called binary fission.


The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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