fly. noun (1) plural flies. Definition of fly (Entry 2 of 6)

Which is correct time flies or time flys?

The correct spelling is “time flies” and not “time flys” because of the rules about spelling verbs that end with “y.”

What is the noun from of fly?

fly. (obsolete) The action of flying; flight. An act of flying.

In general, flies is the only correct version of this word today. If you were writing unusually detailed period fiction about 19th-century Great Britain, you could use flys as a plural noun to refer to a specific mode of transportation.