noun (n)

• the metabolic processes whereby certain organisms obtain energy from organic molecules; processes that take place in the cells and tissues during which energy is released and carbon dioxide is produced and absorbed by the blood to be transported to the lungs(noun.act)

  Synonym:
  cellular respiration, internal respiration
  

  source: wordnet30
• a single complete act of breathing in and out(noun.act)

  Example:
  Thirty respirations per minute.
  

  source: wordnet30
• the bodily process of inhalation and exhalation; the process of taking in oxygen from inhaled air and releasing carbon dioxide by exhalation(noun.act)

  Synonym:
  breathing, external respiration, ventilation
  

  source: wordnet30
• The act of respiring or breathing again, or catching one's breath.(noun)

  source: webster1913