(also thyroid gland) a large endocrine gland that lies at the base of the neck and produces hormones, e.g. thyroxine, that increase the metabolic rate and influence growth and development
a preparation of mammalian thyroid gland used in treating conditions in which the thyroid gland produces insufficient quantities of hormones
[scientific Latin from Greek thyreoeidēs shield-shaped, thyroid, from thyreos shield shaped like a door, from thyra door]