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Is it Flys or Flies? Which is Correct? (Examples)

Is the correct word flys or flies? When I want to refer to multiple insects, which form of the base word fly do I use? Or when I want to refer to something that has flown through the air, which form of the base form fly do I use? Irregular verbs can be complicated to understand. And use!

In this guide, we’ll go through “flys” vs “flies” as part of the irregular verb “to fly” and how it can get used properly…

Difference between “flys” and “flies”

The words “flys” and “flies” are both homophones. These are words that sound the same but hold different meanings. Because of the very small difference between the two words, they often get confused.

Homophoneone of two or more words pronounced alike but different in meaning or origin or spelling
Irregular verbA verb in which the past tense is not formed by adding the usual -ed ending

The interesting thing is that the singular form of both ‘flys’ and ‘flies’ is ‘fly’. Making it even more confusing for native and non-native English speakers!

The word fly has many meanings. The correct plural form to use depends on the intention of the sentence.

When fly refers to the insect, the plural of the word is ‘flies’ (and not ‘flys’).

Sentence example
Sentence example

While the word fly is a noun, fly is also a verb. It refers to something moving through the air (a bird, an airplane, or Superman).

The word fly, as a noun, has four meanings. Refer to the table below to see each definition of the word “fly.”

Fly (verb) /flī/(of a bird, bat, or insect) move through the air using wings.
Fly (noun) /flī/an opening at the crotch of a pair of pants, closed with a zipper or buttons and typically covered with a flap.

the space over the stage in a theater.

a one-horse hackney carriage.

Does it sound confusing? It certainly does. Let’s understand these words clearly using some basic rules:

  • Fly refers to the zip of a pant (in the crotch region). The zipper is referred to as a fly. The plural of this is flys (many zippers on many pants).
  • The game of baseball has the concept of fly balls that are hit high in the air. Instead of using fly balls, the words ‘flys’ are used to refer to this (many fly balls).
  • The carriages used during the 1800s were referred to as flys. This is another usage where flys refer to more than one carriage.
  • In the theatre world, the area over the stage is called fly. So, when this is referred to in the plural form, flys can be used. Although, it’s seldom that someone would refer to the word “fly” in this context.

The many forms the word “flys” can take are daunting. Flys can get used as a plural for a pant zip, baseball hits, carriages, and theatre stage areas.

Flies is the plural for the insect and the verb fly. And also to refer to the act of flying in the present and past participle form.

Definition of “flies”

The word flies is the plural form of fly. There are two definitions of this word. A noun and verb form definition. Refer to the table below to see those.

Fly (verb)Third person present
Flies (verb)Past tense
FlyingPast participle: flown
Flew (gerund)Gerund or present participle

The noun fly refers to a tiny insect with wings. The insect is known to be irritating as it hovers around food. The plural of the word fly is ‘flies.’ Using ‘flys’ to indicate multiple insects is considered a grammatical error.

For example:

  • The moment I opened the windows, many flies entered the room, making a beeline for the sweets.
  • The eagle flies high in the air gracefully and exhibits its sheer power.

Definition of “flys”

Remember, the word “fly” is a noun that can mean any one of the following:

  • A pant zipper.
  • A baseball hit.
  • Old carriages used in the 1800s.
  • The area above the stage in a theatre.

The plural of these noun forms is ‘flys.’

Sentence example
Sentence example

When to use “flies”

Flies gets used as the plural of the noun fly, which means insect. It is also used as the plural of the verb fly, which means move in the air.

Sentence examples

  • I saw a lot of flies sitting on the sweets. I wouldn’t eat it.
  • The falcon flies in the sky the moment its master gestures.

When to use “flys”

Flys is the proper usage only when “fly” is used as a noun referring to a pant zipper, baseball hits, or other definitions.

Sentence examples

  • We all covered the flys on our pants.
  • There were many flys as the batter went berserk with his hitting.
  • There were flys lined up in the exhibition.

How to remember which form to use

For all practical purposes, only two meanings of fly get used most often.

One is the insect, and the other moving in the air. For both these words, the rule is very clear.

If you’re flying through the area, the present participle and past participle would be: flies.

For example, “She flies through the air like a bird.”

Sentence example
Sentence example

When referring to insects and having many insects, use “flies” as well.

For example, “There are a lot of flies in this room.”

Use “flys” only when referring to the past participle of multiple zippers or other associations that match with the definition of “fly” in the correct form you’re intending.

For example, “All the men had their flys removed for some odd reason!” (Incorrect)

Understanding the “flys” or “flies” verb variations

Let’s focus on the verb fly. Fly as a verb can refer to moving through the air.

The verb fly can refer to a bird or insect flying, too. It can refer to a flag fluttering in the air. It can also refer to any object moving fast in the air. The verb is used to refer to the passage of time.

  • In the present tense, the correct word is fly.
  • The past simple of fly is flew.
  • The past participle of fly is flown.
  • When used as a present participle, flying has to be used.

The following examples illustrate this:

  • I would like to fly in the sky with wings on.
  • The parrot flew above the tree, fluttering its wings as it tried to soar high.
  • I have flown many kites as a child.
  • I am flying to New York this weekend.

Common questions

Questions about the English language.

Is it “time flies” or “time flys?”

The correct phrase is “time flies.” For example, “Time flies when you’re having fun!”


  1. Flys or Flies – What’s the Difference?
  2. Flys or Flies – Which Spelling is Correct?
  3. Flies or Flys – Which is Correct?
  4. Flys or Flies – What’s the Difference

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About the author

Dalia Y.: Dalia is an English Major and linguistics expert with an additional degree in Psychology. Dalia has featured articles on Forbes, Inc, Fast Company, Grammarly, and many more. She covers English, ESL, and all things grammar on GrammarBrain.

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