FISvsfoxWhich spelling fits?

Which to use

“FIS” and “fox” are a confusable English pair: similar on the page, but distinct in meaning, check the gloss before you choose.

#40,245
“FIS” frequency rank
#2,204
“fox” frequency rank
42449
confusion score

Side-by-Side Comparison

Feature FIS fox
Definition Initialism of flight information service. A small-to-medium-sized canine mammal, related to dogs and wolves, with a flattened skull, upright triangular ears, a pointed, slightly upturned snout, and a long bushy tail, of the following groups:

Letter map: FIS vs fox

Shared letters muted; letters that set FIS and fox apart highlighted. Shared run: 1.

3 ch
FIS
3 ch
fox

Pair insight - FIS / fox

FIS and fox are indexed as a confusable English pair. We have no recorded pronunciation or part of speech for both members, so the spelling overlap is what we can show you: they share most of their letters but differ in 2 positions. Our composite confusion score for this pair is 42449, derived from the frequency rank of both members and their visual similarity.

FIS is recorded at frequency rank #40,245, classified as anoun. fox is at rank #2,204, tagged as anoun, pronounced /fɒks/.

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 42449, this pair ranks #249,094 of 530,003 scored English confusable pairs - roughly mid-pack for confusability.

Orthographic DNA of FIS vs fox

Shared letters: f. Private to "FIS": is. Private to "fox": ox.

"FIS" · 3 letters · shape CVC  ·  "fox" · 3 letters · shape CVC

Frequently Asked Questions

Is swapping "FIS" for "fox" ever safe?
No. They share most of their letters but differ in 2 positions, but the dictionary glosses above give them different meanings, so swapping one for the other changes what the sentence says.
In ordinary English text, does "FIS" or "fox" show up more?
"fox" is the more common of the two: it sits at frequency rank #2,204 in our English list, against #40,245 for "FIS". That is a wide gap, so in ordinary text the rarer spelling is the one worth double-checking.

After this comparison

Done with this confusable. These links stay specific to "FIS" and "fox".

  • Full dictionary entry for "FIS" with definition, IPA, and generated misspellings. Word entry
  • Full dictionary entry for "fox" - compare definitions side by side with the headword page. Word entry
  • This pair ranks #249,094 of 530,003 scored English confusable pairs in this corpus vintage. Corpus statistics
  • "FIS" and "fox" also get mixed up with nearby pairs, the highest-scored neighbour is "FIS vs foh". Nearby pair

Confusion rank #249,094 of 530,003 scored English pairs, corpus vintage 2026-09-03, not spelling advice.

Source: Wiktionary (via kaikki.org) Structured Wiktionary extract

Source: FrequencyWords open word-frequency list