- The definition of a mayfly is a thin insect with delicate wings that only lives a few days.
An example of a mayfly is a thin and delicate insect.
The adult mayfly or dayfly.
any of an order (Ephemeroptera) of delicate, soft-bodied insects with gauzy wings held vertically when at rest: in the adult stage, it lives only hours or a few days, but the aquatic larval stage may last for several years
Origin of mayflyso named because thought to be most prevalent in May
Any of various delicate, winged insects of the order Ephemeroptera that develop from aquatic nymphs and in the adult stage live no longer than a few days and do not feed.