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thyroxine Line breaks: thy¦rox|ine
Pronunciation: /θʌɪˈrɒksiːn/

Definition of thyroxine in English:


[mass noun] Biochemistry
The main hormone produced by the thyroid gland, acting to increase metabolic rate and so regulating growth and development.
  • An iodine-containing amino acid; chemical formula: C15H11NO4I4
Example sentences
  • The thyroid releases too much of the hormone thyroxine, which increases the person's basal metabolic rate.
  • Human beings require iodine for the production of the thyroid hormones, thyroxine and triiodothyronine.
  • When your thyroid gland produces too much of the hormone thyroxine, you develop hyperthyroidism.


Early 20th century: from thyroid + ox- 'oxygen' + in from indole (because of an early misunderstanding of its chemical structure), altered by substitution of -ine4.

Definition of thyroxine in:
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