System (Selected definitions) sys·tem (sîsątem) noun Abbr. syst. 1. A group of interacting, interrelated, or Interdependent elements forming a complex whole. 2. A functionally related group of elements 8. An organized and coordinated method; a procedure. See synonyms at METHOD. . The American Heritage® Dictionary of the English Language, Third Edition copyright © 1992 by Houghton Mifflin Company. Electronic version licensed from InfoSoft International, Inc. All rights reserved.