hyperthyroidism hy·per·thy·roid·ism (hī'pər-thī'roi-dĭz'əm)
Pathologically excessive production of thyroid hormones.
The condition resulting from excessive activity of the thyroid gland, characterized by increased basal metabolism.
An abnormality of the thyroid gland characterized by excessive production of thyroid hormone, which can result in an increased basal metabolic rate, causing weight loss, heart palpitations, and tremors. Compare hypothyroidism.