"Stab in the back" is a phrase used to describe when someone betrays or disappoints someone they once trusted. There are many synonyms for this phrase that can be used interchangeably in different contexts. One such synonym is "double-cross," which refers to a situation where someone is betrayed by someone else they thought they could rely on. Another possible synonym is "backstab," which is similar in meaning to the original phrase but more informal. Other synonyms for "stab in the back" may include "treachery," "betrayal," "deceit," or "disloyalty." No matter which synonym is used, the meaning remains the same: a breach of trust that causes deep hurt and disappointment.