Definition of thyroxine in English:

Share this entry


Pronunciation: /THīˈräksən/
Pronunciation: /THīˈräkˌsēn/
(also thyroxin /-sin/)


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.

For editors and proofreaders

Syllabification: thy·rox·ine

Share this entry

What do you find interesting about this word or phrase?

Comments that don't adhere to our Community Guidelines may be moderated or removed.