Thyroxine

[Agnes]

a hormone produced by the thyroid gland that controls metabolism (= chemical processes in the body) and is important for normal development in children

[PussyCat]

the main chemical produced in the body by the thyroid (gland) (= organ in the neck) , which increases the metabolism (= changing of food into energy) and in this way, makes the body grow and develop

[Rihanna]

The main hormone produced by the thyroid gland, acting to increase metabolic rate and so regulating growth and development.