An "open-and-shut case" refers to a situation that is straightforward and clear-cut, with no room for doubt or debate. Some synonyms for this phrase include "cut-and-dried," "clear-cut," "unambiguous," and "unequivocal." Other related words include "apparent," "obvious," and "self-evident," which also convey the idea of a situation that is easily understood or readily apparent. Alternatively, phrases such as "slam dunk," "no-brainer," and "a done deal" suggest that a decision or outcome is inevitable or already decided, leaving little room for discussion or argument. Regardless of the specific wording used, these phrases all convey a sense of certainty and finality.