athyroidism a·thy·roid·ism (ā-thī'roi-dĭz'əm, ə-thī'-) or a·thy·re·a (ā-thī'rē-ə, ə-thī'-) or a·thy·ro·sis (ā'thī-rō'sĭs, āth'ī-) n. The absence of the thyroid gland or the suppression of its secretion.
