Definition of mayfly
: any of an order (Ephemeroptera) of insects with an aquatic nymph and a short-lived, fragile adult lacking mouthparts and having membranous, heavily veined wings and two or three long, threadlike tails ◆the wings of the mayfly are held vertically above the body when closed. —called also ephemerid
First Known Use of mayfly
MAYFLY Defined for English Language Learners
Definition of mayfly for English Language Learners
: a small flying insect that lives for only a short time
Seen and Heard
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