1. Anything that is shortlived or lives but for a day.

Nuttall's Standard dictionary of the English language By Nuttall, P.Austin

• ephemeral,
• wphemeron,
• sphemeron,
• dphemeron,
• rphemeron,
• 4phemeron,
• 3phemeron,
• eohemeron,
• elhemeron,
• e-hemeron,
• e0hemeron,
• epgemeron,
• epbemeron,
• epnemeron,
• epjemeron,
• ehemeron,
• ephmeron,
• Ephameron,
• Ephamaron,
• Ehemmeron

• ephemerid,
• ephemeris,
• ephemerida,
• ephemeral,
• ephemeridae,
• ephemera,
• ephemerality.

The adjective form of the word "ephemeron" is "ephemeral".