Which to use
“FOSS” is a noun and “FTSE” is a name - they look or sound alike but fill different roles in a sentence.
- #33,655
- “FOSS” frequency rank
- #38,851
- “FTSE” frequency rank
- 72506
- confusion score
Side-by-Side Comparison
| Feature | FOSS | FTSE |
|---|---|---|
| Definition | Initialism of Free and Open Source Software. | Financial Times and Stock Exchange. |
Where the eye mixes FOSS and FTSE
Muted = shared; highlighted = the visual trap. They share 2 letters in sequence.
Visual trap between FOSS and FTSE
These two trip readers on the page rather than in the ear: FOSS is /fɒs/ while FTSE is /ˈfʊt.si/. Spoken aloud the problem disappears. In writing it persists, because they share most of their letters but differ in 2 positions, and the parts of speech differ too (noun vs name), which is usually the fastest check. Our composite confusion score for this pair is 72506, derived from the frequency rank of both members and their visual similarity.
FOSS is recorded at frequency rank #33,655, classified as anoun, pronounced /fɒs/. FTSE is at rank #38,851, tagged as aname, pronounced /ˈfʊt.si/.
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 72506, this pair ranks #42,757 of 530,003 scored English confusable pairs - among the most confusable pairs.
Orthographic DNA of FOSS vs FTSE
Shared letters: fs. Private to "FOSS": o. Private to "FTSE": et.
"FOSS" · 4 letters · shape CVCC · "FTSE" · 4 letters · shape CCCV
Known mistypes of this pair
Frequently Asked Questions
Can "FOSS" and "FTSE" be used interchangeably?
Frequency check: "FOSS" vs "FTSE" - which ranks higher?
Useful next steps
Visual near-miss handled. Browse the word pages or a neighbour when the next look-alike shows up.
- Full dictionary entry for "FOSS" with definition, IPA, and generated misspellings. Word entry
- Full dictionary entry for "FTSE" - compare definitions side by side with the headword page. Word entry
- This pair ranks #42,757 of 530,003 scored English confusable pairs in this corpus vintage. Corpus statistics
- "FOSS" and "FTSE" also get mixed up with nearby pairs, the highest-scored neighbour is "fie vs FTSE". Nearby pair
- Recorded mistypes exist for at least one side of this pair, useful when a spell-checker or OCR lands on the wrong form. See mistypes
Confusion rank #42,757 of 530,003 scored English pairs, corpus vintage 2026-09-03, not spelling advice.