Ghost chance is a term that refers to a very slim possibility or a chance that is unlikely to happen. There are many synonyms that can be used to express the same meaning. For instance, the term "slim chance," or "long shot," denotes a probability that is remote or unlikely. Other synonyms for ghost chance include long odds, outside chance, a snowball's chance in hell and one in a million chances. Essentially, the term ghost chance is often used to describe a possibility that is hard to achieve or unlikely to happen, and it can be replaced with any of the above synonyms depending on the context in which it is used.