thy ‧ roid /ˈθaɪrɔɪd/ BrE AmE ( also ˈthyroid ˌgland ) noun [countable]
[ Date: 1700-1800 ; Language: Modern Latin ; Origin: thyroides , from Greek thyreoeides 'shield-shaped' , from thyreos 'shield shaped like a door' , from thyra 'door' ; from the shape of the cartilage at the front of the throat ]
an organ in your neck that produces substances that affect the way your body grows and the way you behave