Noun | 1. | hyperthyroidism - an overactive thyroid gland; pathologically excessive production of thyroid hormones or the condition resulting from excessive production of thyroid hormones adenosis, gland disease, glandular disease, glandular disorder - a disorder of the glands of the body exophthalmic goiter, Graves' disease - exophthalmos occurring in association with goiter; hyperthyroidism with protrusion of the eyeballs exophthalmos - protrusion of the eyeball from the socket hypothyroidism - an underactive thyroid gland; a glandular disorder resulting from insufficient production of thyroid hormones |