Every unique language is assigned a three-letter code based on ISO 639-3 specifications. Information on these codes, and the data files used here, can be accessed here. (As you may now need a subscription to Ethnologue, also check out SIL and Glottolog.)

Also present in the world are languages whose names are three letters long (when in romanization). For this part, the language name is that in the primary ‘Name’ field of the Ethnologue data. Of the 7,000+ languages in Ethnologue, 235 have three-letter names, and of these, 58 of these are ISO-morphic: where the Name matches the ISO code.

The languages themselves are listed below, for your undoubtedly essential reference.

ISO-morphic languages

  1. Adi
  2. Aja
  3. Amo
  4. Ayu
  5. Cua
  6. Dek
  7. Dem
  8. Dia
  9. Doe
  10. Efe
  11. Ega
  12. Eki
  13. Elu
  14. Enu
  15. Fam
  16. Foi
  17. Fon
  18. Fum
  19. Fwe
  20. Hiw
  21. Hre
  22. Hya
  23. Ibu
  24. Idi
  25. Isu
  26. Jeh
  27. Kei
  28. Ket
  29. Kis
  30. Kol
  31. Lao
  32. Liv
  33. Mam
  34. Mbo
  35. Nii
  36. Noy
  37. Oku
  38. Omi
  39. Ona
  40. Oti
  41. Rao
  42. Tal
  43. Tiv
  44. Ubi
  45. Uda
  46. Udi
  47. Utu
  48. Vai
  49. Vao
  50. Wab
  51. Wan
  52. Weh
  53. Wom
  54. Yao
  55. Yis
  56. Yoy
  57. Yug
  58. Zia

Weakly ISO-morphic languages

However, this compares the ISO code with the primary language name. Many languages have alternate names, and named dialects. All this information is available in the LanguageIndex.tab file. Each row is essentially an LangID, Name pair where the name is tagged as either primary, alternate, dialect, or alternate dialect. We can go further (why though?) by collecting all languages that contain any kind of alternate name or dialect that is ISO-morphic. These additional weakly ISO-morphic languages are shown below: at least one of the alternate names for or dialects of these languages is ISO-morphic

  1. Dangme
  2. Eloyi
  3. Amis
  4. Pele-Ata
  5. Tibetan, Central
  6. Karen, Bwe
  7. Ibaas
  8. Day
  9. Dass
  10. Dyan
  11. Egyptian Sign Language
  12. Ezaa
  13. Guatemalan Sign Language
  14. Mbato
  15. Horo
  16. Hawaii Sign Language
  17. Iaai
  18. Igbo
  19. Ede Ica
  20. Inku
  21. Yei
  22. Dza
  23. Japanese Sign Language
  24. Dholuo
  25. Luwo
  26. Mru
  27. Samba Leko
  28. Yuanga
  29. Ngwe
  30. Pe
  31. Krumen, Pye
  32. Tarifit
  33. Meskwaki
  34. Seke
  35. Yami
  36. Udihe
  37. Fungwa
  38. Uya
  39. Ute-Southern Paiute
  40. Flemish Sign Language
  41. |Xam
  42. Chinese, Yue

You’re welcome? Anyway, here’s the code.