hypothyroidism

/ˌhaɪpoʊˈθaɪrɔɪdɪzəm/

hypo·thy·roid·ism

BrE /ˌhaɪpəʊˈθaɪrɔɪdɪzəm/

NAmE /ˌhaɪpoʊˈθaɪrɔɪdɪzəm/

[U] (medical)

a condition in which the thyroid is not active enough, making growth and mental development slower than normal