Adenoids, lymphoid tissue at the back of the throat, which usually shrinks and disappears by adolescence. Enlargement of this tissue, however, is fairly common in children and may interfere with breathing. Symptoms of enlarged adenoids include a nasal voice, persistent breathing through the mouth, snoring, and restless sleep. Formerly these tissues were routinely removed in children, because it was thought that inflamed adenoids led to recurrent infections and colds. More recently, medical science has recognized this condition as usually benign, and the number of adenoidectomies has consequently declined. See also Tonsil.