fly

1. fly (noun) — sense 1

Definition: Any insect of the order Diptera; characterized by having two wings (except for some wingless species), also called true flies.

Example: Devils Lake is where I began my career as a limnologist in 1964, studying the lake’s neotenic salamanders and chironomids, or midge flies. […] The Devils Lake Basin is an endorheic, or closed, basin covering about 9,800 square kilometers in northeastern North Dakota.

2. fly (noun) — sense 2

Definition: Especially, any of the insects of the family Muscidae, such as the common housefly (other families of Diptera include mosquitoes and midges).

Example: When you're well enough off so's you don't have to fret about anything but your heft or your diseases you begin to get queer, I suppose. And the queerer the cure for those ailings the bigger the attraction. A place like the Right Livers' Rest was bound to draw freaks, same as molasses draws flies.

3. fly (noun) — sense 3

Definition: Those or any similar but not closely related insect, such as a dragonfly, butterfly, or gallfly.