fails vs FIS, What's the Difference?

Which to use

“fails” is a verb and “FIS” is a noun - they look or sound alike but fill different roles in a sentence.

#4,600
“fails” frequency rank: #40,245
“FIS” frequency rank: 44845
confusion score

Side-by-Side Comparison

Feature	fails	FIS
Definition	third-person singular simple present indicative of fail	Initialism of flight information service.

Where the spellings diverge

Shared letters are muted; the letters that actually set fails and FIS apart are highlighted. They share 3 letters in sequence, which is exactly why the eye skips the difference.

5 ch

fails

3 ch

FIS

Spelling & Dictionary Insight

Our dataset has no pronunciation recorded for both members, so the reliable separator here is grammatical: fails is averb and FISanoun. On the page they differ by 2 letter(s) in length. Our composite confusion score for this pair is 44845, derived from the frequency rank of both members and their visual similarity.

fails is recorded at frequency rank #4,600, classified as averb, pronounced /feɪlz/. FIS is at rank #40,245, tagged as anoun.

Glosses for this pair are partially populated in our dataset, but the full side-by-side definitions above should still guide you to the right choice.

With a confusion score of 44845, this pair ranks #226,794 of 530,003 scored English confusable pairs - roughly mid-pack for confusability.

Orthographic DNA of fails vs FIS

Shared letters: fis. Private to "fails": al. Private to "FIS": -.

"fails" · 5 letters · shape CVVCC · "FIS" · 3 letters · shape CVC

Known mistypes of this pair

fails ← afils · faills · failss · faisl · falis · ffails · fials

Frequency comparison

fails#4,600

FIS#40,245

Source: FrequencyWords open word-frequency list

Frequently Asked Questions

Can "fails" and "FIS" be used interchangeably?

No - they are not even the same part of speech. "fails" is a verb and "FIS" a noun, so a sentence built for one is usually ungrammatical with the other.

Which is more common, "fails" or "FIS"?

"fails" is the more common of the two: it sits at frequency rank #4,600 in our English list, against #40,245 for "FIS". The two are close in frequency, so neither is a safe default; check the meaning rather than guessing.

Remembering fails vs FIS

The fastest way to pick the right one every time.

Check the role first: if you need a verb, it's “fails”; for a noun, it's “FIS”.
See each word in full, definition, IPA, etymology and its other confusables. Full “fails” entry
Browse more pairs most likely to be confused. Most confusable