The term RESPIRATION ORGAN is referring to the LUNG, which is a four letter word. The lungs are organs located in the chest cavity and are responsible for respiration, or the process of taking in oxygen and releasing carbon dioxide. They are part of the respiratory system, which also includes the nose, throat, and trachea. The lungs are made up of millions of tiny air sacs called alveoli, which allow oxygen to enter the bloodstream and carbon dioxide to be released.