third tonsil
      n : 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" [syn: pharyngeal tonsil, adenoid,
           Luschka's tonsil, tonsilla pharyngealis, {tonsilla
          adenoidea]