| Noun | 1. | third tonsil - a collection of lymphatic tissue in the throat behind the uvula (on the posterior wall and roof of the nasopharynx); "hypertrophy of the pharyngeal tonsils is called adenoids"; "enlarged adenoids may restrict the breathing of children"pharynx, throat - the passage to the stomach and lungs; in the front part of the neck below the chin and above the collarbone | |