Consensual Non Monogamy (CNM) or Ethical Non-Monogamy (ENM) is an umbrella term the different types of non monogamous relationships that exist. Every individual's CNM is different and is based on the communication, understanding and explicitly agreeing to the set rules in their relationships. Some of the terms in CNM are polyamory, swinging, open relationships, monogam-ish, solo-poly, among others.
Sources:
https://www.mindbodygreen.com/articles/ethical-non-monogamy-guide