hyperthyroidismPronunciation: /ˌhʌɪpəˈθʌɪrɔɪdɪz(ə)m/Definition of hyperthyroidism noun [mass noun] Medicine overactivity of the thyroid gland, resulting in a rapid heartbeat and an increased rate of metabolism. Also called thyrotoxicosis.Derivatives hyperthyroid adjective hyperthyroidic adjective hyperthyroidism in other Oxford dictionaries Definition of hyperthyroidism in the US English dictionary
