kəʊˈɪʃ(ə)n ˈkəʊ.ɪ.təs ˈkɔɪ.təs kɒp.jəˈleɪ.ʃən ˈɪn.tɚˌkɔɹs ˈɪn.təˌkɔːs ɹɪˈleɪʃən ˈɹɛl.ə.tɪv an abstraction belonging to or characteristic of two entities or parts together (usually plural) mutual dealings or connections among persons or groups international relations sexual activity between individuals, especially the insertion of a man's penis into a woman's vagina until orgasm and ejaculation occur (law) the principle that an act done at a later time is deemed by law to have occurred at an earlier time his attorney argued for the relation back of the amended complaint to the time the initial complaint was filed an act of narration he was the hero according to his own relation his endless recounting of the incident eventually became unbearable a person related by blood or marriage police are searching for relatives of the deceased he has distant relations back in New Jersey