Off-chance is commonly used to refer to a possibility or opportunity that is unexpected or unlikely. Some synonyms for this expression include "long shot," "slim hope," "remote possibility," or "faint possibility." Another word that captures the essence of off-chance is "serendipity," which refers to a fortunate discovery or occurrence that happens by chance. Other related words that can be used to describe off-chance include "chance occurrence," "stroke of luck," or "happy accident." Regardless of the synonym you choose, they all convey the same message - the potential for a positive outcome based on a happening that is uncertain.