/may"fluy'/ , n. , pl. mayflies .
1. Also called shadfly . any insect of the order Ephemeroptera, having delicate, membranous wings with the front pair much larger than the rear and having an aquatic larval stage and a terrestrial adult stage usually lasting less than two days.
2. Also, May fly . Angling. an artificial fly made to resemble this insect.
[ 1645-55; MAY + FLY 2 ]