(n.) An assemblage of parts or organs, either in animal or plant, essential to the performance of some particular function or functions which as a rule are of greater complexity than those manifested by a single organ; as, the capillary system, the muscular system, the digestive system, etc.; hence, the whole body as a functional unity.
Meaning of SYSTEM in English
Webster's English dictionary. Английский словарь Webster. 2012