Flash pan is a term used to describe something that is short-lived or fleeting. There are several synonyms that can be used to convey this same meaning. One such synonym is a "flash in the pan," which is a similar term that describes something that quickly rises to success and then just as quickly fades away. Another synonym for flash pan is a "one-hit wonder," which refers to a person or thing that achieves sudden and brief success but is unable to replicate that success a second time. "Ephemeral" and "transitory" are other synonyms for flash pan that can also be used to describe something that is short-lived or fleeting.