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[ser-uh-toh-nin, seer-] /ˌsɛr əˈtoʊ nɪn, ˌsɪər-/
noun, Biochemistry
a neurotransmitter, derived from tryptophan, that is involved in sleep, depression, memory, and other neurological processes.
Origin of serotonin
1945-50; sero- + tone + -in2 Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2015.
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British Dictionary definitions for serotonin


a compound that occurs in the brain, intestines, and blood platelets and acts as a neurotransmitter, as well as inducing vasoconstriction and contraction of smooth muscle; 5-hydroxytryptamine (5HT)
Word Origin
from sero- + ton(ic) + -in
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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Word Origin and History for serotonin

neurotransmitting chemical, 1948, coined from sero-, comb. form of serum (q.v.) + ton(ic) + chemical suffix -in (2).

Online Etymology Dictionary, © 2010 Douglas Harper
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serotonin in Medicine

serotonin se·ro·to·nin (sěr'ə-tō'nĭn, sēr'-)
An organic compound formed from tryptophan and found in animal and human tissue, especially the brain, blood serum, and gastric mucous membranes, and active in vasoconstriction, stimulation of the smooth muscles, transmission of impulses between nerve cells, and regulation of cyclic body processes. Also called 5-hydroxytryptamine.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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serotonin in Science
  (sěr'ə-tō'nĭn, sîr'-)   
A monoamine substance that is formed from tryptophan and found in many animal tissues, including the intestine and central nervous system. In the brain, serotonin acts as a neurotransmitter that is involved in the control of pain perception, the sleep-wake cycle, and mood. Serotonin is also produced in some bacteria and plants.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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