Synonyms for Ephemeral (same or very similar meaning)
WordNet sense 1 (anything short-lived, as an insect that lives only for a day in its winged form):
ephemeron
WordNet sense 2 (lasting a very short time):
passing, short-lived, transient, transitory, fugacious
WordNet sense 3 (not permanent; not lasting):
temporary
From the ODE community, based on WordNet
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