Multiamorous is a polyamorous relationship, in which every partner has different relationships with one another. An example would be that A and B are in a romantic relationship, B and C are in a sexual relationship, and A and C are in a queerplatonic relationship.
History
The term was coined by fandom user Cryptocrew, on November 24th, 2020 to fit the definition of a term an anomynous user described, that was not yet coined.