Day"fly` (?), n. Zool.
A neuropterous insect of the genus Ephemera and related genera, of many species, and inhabiting fresh water in the larval state; the ephemeral fly; -- so called because it commonly lives but one day in the winged or adult state. See Ephemeral fly, under Ephemeral.
<-- the Mayfly? = ephemerid of order ephemeroptera -->
© Webster 1913.