Vowel Harmony
A characteristic feature of the Mongolian language is that of vowel harmony, a feature which is also common in Turkish and to a lesser extent in Manchurian as well. The concept of vowel harmony is extremely straightforward, and simply means that a word can only contain either back vowels (a, o, u) or front vowels (e, ö, ü), but not both at the same time, with the exception only of a certain limited amount of words, the majority of which are foreign. The vowel i is considered neutral and can therefore occur in both front and back voweled words, but when i occurs in all syllables the word is considered to be front voweled. Vowel harmony also affects two other sets of letters, γ/q and g/k, with the former occurring only in back-voweled words and the latter only in front-voweled words.
Examples of back vowel words
Back voweled word can only contain the back vowels a, o and u or the neutral vowel i, and cannot contain the consonants g and k (except when k is followed by the letter i).
| čaγan (white) | 
| aγulan (mountain) | 
| noyan (prince) | 
| soyul (culture) |
| ama (mouth) | 
| ulaγan (red) | 
| balai (stupid) |
Examples of front vowel words
Front voweled word can only contain the front vowels e, ö and ü or the neutral vowel i, and cannot contain the consonants γ and q (except in a small and limited number of words).
| beleg (gift) | 
| nökör (comrade) | 
| tümen (ten thousand) | 
| sedkil (thought) |
| ner-e (name) | 
| edüge (now) | 
| ünen (truth) |
Examples of front and back-voweled words containing 'i'
Front neutral vowel i can occur alongside all vowels (back and front) and all consonants.
| imaγan (goat) | 
| nidün (eye) | 
| jirγal (bliss) | 
| yirtinčü (universe) |
| irgen (people) | 
| joriγ (intention) | 
| qoni (sheep) |
Examples with 'i' in all syllables
When i occurs in all syllables the word is regarded as front vocalic and any suffixes/case markers joined to the word must also be front vocalic.
| bičig (writing, book) | 
| bilig (wisdom) | 
| čikibči (ear-muffs) | 
| ilbiči (magician) |
Back vowel words with 'γ' and 'q'
Only back-voweled words can contain the consonants γ and q, with the exception of a limited number of words (see below)
| qaγan (khan) | 
| γajar (place) | 
| qoitu (north) | 
| ijaγur (origin) |
Front vowel words with 'g' and 'k'
Only front-voweled words can contain the consonants g and k, with the exception of a limited number of words (see below) and when k is followed by the letter i.
| kümün (person) | 
| ger (home, ger) | 
| kejiy-e (when?) | 
| köbegün (boy, son) |
Examples of words which violate vowel harmony
A very small number of nouns break from the rules of vowel harmony, these are mainly words of foreign origin.
| türkestan (Turkestan) | 
| kunda (jasmin) (Sanskrit) | 
| guoši (teacher) (Chinese) |