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[thahy-rok-seen, -sin] /θaɪˈrɒk sin, -sɪn/
Biochemistry. the thyroid gland hormone that regulates the metabolic rate of the body.
Pharmacology. a commercial form of this compound, obtained from the thyroid glands of animals or synthesized, used in the treatment of hypothyroidism. Symbol: T 4.
Also, thyroxin
[thahy-rok-sin] /θaɪˈrɒk sɪn/ (Show IPA)
Origin of thyroxine
1915-20; thyr- + ox- + in(dol)e (orig. thought to be a chemical component) Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2018.
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British Dictionary definitions for thyroxin


/θaɪˈrɒksiːn; -sɪn/
the principal hormone produced by the thyroid gland: it increases the metabolic rate of tissues and also controls growth, as in amphibian metamorphosis. It can be synthesized or extracted from the thyroid glands of animals and used to treat hypothyroidism. Chemical name: tetra-iodothyronine; formula: C15H11I4NO4
Word Origin
C19: from thyro- + oxy-² + -ine²
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 thyroxin



from thyro-, comb. form of thyroid, + oxy- + indole + chemical suffix -ine (2). So called from the original description of its composition.

Online Etymology Dictionary, © 2010 Douglas Harper
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thyroxin in Medicine

thyroxine thy·rox·ine (thī-rŏk'sēn', -sĭn) or thy·rox·in (-rŏk'sĭn)
Abbr. T4
An iodine-containing hormone that is produced by the thyroid gland, increases the rate of cell metabolism, regulates growth, and is made synthetically for treatment of thyroid disorders.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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thyroxin in Science
  (thī-rŏk'sēn', -sĭn)   
An iodine-containing hormone secreted by the thyroid gland that increases the rate of cell metabolism and regulates growth. Thyroxine can also be made synthetically for treatment of hypothyroidism.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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