| Name | Other Name | Family | Nativ Name | ISO6391 Code | ISO6392T Code | ISO6392B Code | ISO6393 Code | Notes |
|---|---|---|---|---|---|---|---|---|
| Latin | Indo-European | latine; lingua latina | la | lat | lat | lat | ancient | |
| Lao | Tai–Kadai | ພາສາລາວ | lo | lao | lao | lao | ||
| Kurdish | Indo-European | Kurdî; كوردی | ku | kur | kur | kur + 3 | macrolanguage | |
| Kuanyama | Kwanyama | Niger–Congo | Kuanyama | kj | kua | kua | kua | |
| Korean | Koreanic | 한국어 | ko | kor | kor | kor | ||
| Kongo | Niger–Congo | Kikongo | kg | kon | kon | kon + 3 | macrolanguage | |
| Komi | Uralic | коми кыв | kv | kom | kom | kom + 2 | macrolanguage | |
| Kirghiz | Kyrgyz | Turkic | Кыргызча; Кыргыз тили | ky | kir | kir | kir | |
| Kinyarwanda | Niger–Congo | Ikinyarwanda | rw | kin | kin | kin | ||
| Kikuyu | Gikuyu | Niger–Congo | Gĩkũyũ | ki | kik | kik | kik |