- 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.
mayfly definition by Webster's New World
Webster's New World College Dictionary Copyright © 2010 by Wiley Publishing, Inc., Cleveland, Ohio. Used by arrangement with John Wiley & Sons, Inc.
noun pl. mayflies
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: so named because thought to be most prevalent in May
mayfly definition by American Heritage Dictionary
Any of various fragile winged insects of the order Ephemeroptera that develop from aquatic nymphs and live in the adult stage no longer than a few days. Also called dayfly, shadfly.