Ephemerida is a term used to describe something that is short-lived, transitory or fleeting. Synonyms for this word include words like fleeting, transitory, temporary, impermanent, evanescent, short-lived, fleeting, momentary, passing, and short-term, among others. These words all describe something that does not last for a long time or is not permanent. Ephemerida can describe anything from a short-lived insect to a passing emotion or fad. It can also describe something that is of passing interest or importance, and is often associated with things that are ephemeral or of little significance. Using synonyms for this word can help to add variety and depth to your writing or conversation, and can help to convey a more specific meaning.