adenoids (ădˈənoidzˌ) [key], common name for the pharyngeal tonsils, spongy masses of lymphoid tissue that occupy the nasopharynx, the space between the back of the nose and the throat. Normally the adenoids, like the palatine tonsils located on either side of the throat, help prevent infection in the surrounding tissues. However, when they become enlarged they interfere with normal breathing and sometimes with hearing. When severely enlarged, adenoids can affect normal dental development, resulting in an alteration of facial expression. Infection of the adenoids is common, the symptoms resembling those of tonsillitis, with which it is frequently associated. Surgical removal of the adenoids is advisable when enlargement and repeated infection interfere with development and health. See respiration.