Definition:
thyroid gland (THY-royd...)
A gland located beneath the larynx (voice box) that makes thyroid hormone and calcitonin. The thyroid gland helps regulate growth and metabolism. Also called thyroid.
Enlarge Anatomy of the thyroid and parathyroid glands; drawing shows the thyroid gland at the base of the throat near the trachea. An inset shows the front and back views. The front view shows that the thyroid is shaped like a butterfly, with the right lobe and left lobe connected by a thin piece of tissue called the isthmus. The back view shows the four pea-sized parathyroid glands. The larynx is also shown.

Anatomy of the thyroid and parathyroid glands. The thyroid gland lies at the base of the throat near the trachea. It is shaped like a butterfly, with the right lobe and left lobe connected by a thin piece of tissue called the isthmus. The parathyroid glands are four pea-sized organs found in the neck near the thyroid. The thyroid and parathyroid glands make hormones.