ephemeron n 1: anything short-lived, as an insect that lives only for a day in its winged form [syn: {ephemeron}, {ephemeral}]
Ephemeron \E*phem"e*ron\, n.; pl. {Ephemera}. [NL. See {Ephemera}.] (Zo["o]l.) One of the ephemeral flies. [1913 Webster]