Isograms: The Longest Words With No Repeated Letters
An isogram is a word in which no letter appears more than once. The longest in our dictionary have 15 letters: DERMATOGLYPHICS (the study of fingerprints and skin patterns) and UNCOPYRIGHTABLE. Among everyday words, the longest are 12 letters: CONSIDERABLY, DEMOGRAPHICS and UNFORGIVABLE.
Key facts
- DERMATOGLYPHICS and UNCOPYRIGHTABLE are 15-letter isograms.
- The longest common isograms have 12 letters: CONSIDERABLY, DEMOGRAPHICS, UNFORGIVABLE.
- 98% of two-letter words are isograms, but only 33% of seven-letter words and 5% of ten-letter words.
- Isograms make strong Wordle guesses because every letter tests something new.
How common are isograms?
Short words almost never repeat a letter: 98% of two-letter words and 90% of three-letter words are isograms. The share falls quickly as words get longer.
| Word length | Isograms |
|---|---|
| 4 letters | 79.7% |
| 5 letters | 65.6% |
| 6 letters | 47.6% |
| 7 letters | 33.1% |
| 8 letters | 20.6% |
| 9 letters | 11.2% |
| 10 letters | 5.4% |
| 11 letters | 2.2% |
| 12 letters | 0.6% |
Only about one word in a thousand with 13 or more letters is an isogram.
The longest isograms
| Letters | Words |
|---|---|
| 15 | DERMATOGLYPHICS, UNCOPYRIGHTABLE |
| 14 | AMBIDEXTROUSLY, DERMATOGLYPHIC, TROUBLEMAKINGS |
| 13 | CONSUMPTIVELY, COPYRIGHTABLE, DOCUMENTARILY, HYDROMAGNETIC |
| 12 (common) | CONSIDERABLY, DEMOGRAPHICS, UNFORGIVABLE |
| 11 (common) | ATMOSPHERIC, BACKGROUNDS, COPYRIGHTED, COUNTRYSIDE, DANGEROUSLY |
Why isograms are useful
- In Wordle and similar games, a guess with five different letters tests five letters at once. All of our best Wordle starting words are isograms.
- Isograms make good puzzle answers and passwords for codes where each letter must map to one symbol.
- A seven-letter isogram rack gives you the most possible words, as we found in which seven letters make the most words.
Sources
- Our own analysis of the ENABLE word list. Common words identified using wordfreq.
