Cohabitation: This can be used in a neutral sense but often doesn't capture the negative connotation of "contubernio." Collusion: This term emphasizes the aspect of conspiracy or secretive agreement for deceitful purposes. Conspiracy: Highlights the plotting aspect, often used in contexts involving secret plans. Illicit Association: Captures both the illegal and negative aspects of the term. Unholy Alliance: This phrase can be used to indicate a morally dubious partnership.