firthvsfrithWhich spelling fits?

Which to use

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

#22,972
“firth” frequency rank
#47,063
“frith” frequency rank
70035
confusion score

Side-by-Side Comparison

Feature firth frith
Definition An arm or inlet of the sea; a river estuary. Peace; security.

Where the eye mixes firth and frith

Muted = shared; highlighted = the visual trap. They share 4 letters in sequence.

5 ch
firth
5 ch
frith

Visual trap between firth and frith

A purely visual mix-up. firth (/fɜːθ/) and frith (/fɹɪθ/) are said differently, so reading them aloud is the quickest way to catch the wrong one. On the page they stay close: they differ only by swapping two adjacent letters (ir ↔ ri) - a transposition the eye reads straight past. Our composite confusion score for this pair is 70035, derived from the frequency rank of both members and their visual similarity.

firth is recorded at frequency rank #22,972, classified as anoun, pronounced /fɜːθ/. frith is at rank #47,063, tagged as anoun, pronounced /fɹɪθ/.

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 70035, this pair ranks #52,189 of 530,003 scored English confusable pairs - among the most confusable pairs.

Orthographic DNA of firth vs frith

Shared letters: fhirt. Private to "firth": -. Private to "frith": -.

"firth" · 5 letters · shape CVCCC  ·  "frith" · 5 letters · shape CCVCC

Known mistypes of this pair

  • firthffirth · firht · firrth · firthh · firtth · fitrh · ifrth
  • frithffrith · friht · frithh · fritth · frrith · frtih · rfith

Frequently Asked Questions

Is swapping "firth" for "frith" ever safe?
No. They are said differently (/fɜːθ/ versus /fɹɪθ/) and carry different meanings; reading the sentence aloud is usually enough to catch the wrong one.
In ordinary English text, does "firth" or "frith" show up more?
"firth" is the more common of the two: it sits at frequency rank #22,972 in our English list, against #47,063 for "frith". The two are close in frequency, so neither is a safe default; check the meaning rather than guessing.

After this comparison

Eye-level mix-up between "firth" and "frith" is sorted above. Next: full entries or other pairs that share a letter shape.

  • Full dictionary entry for "firth" with definition, IPA, and generated misspellings. Word entry
  • Full dictionary entry for "frith" - compare definitions side by side with the headword page. Word entry
  • This pair ranks #52,189 of 530,003 scored English confusable pairs in this corpus vintage. Corpus statistics
  • "firth" and "frith" also get mixed up with nearby pairs, the highest-scored neighbour is "frith vs frothy". 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 #52,189 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