Original: Adenoids (or pharyngeal tonsils, or nasopharyngeal tonsils) are a mass of lymphoid tissue situated at the very back of the nose, in the roof of the nasopharynx, where the nose blends into the mouth.
Simplified: Adenoids (also called pharyngeal tonsils, or nasopharyngeal tonsils) are tissues at the very back of the nose, in the roof of the nasopharynx, where the nose blends into the mouth.