The Mongolian has 7 cases (or function) and Ablative is one of them.
This case is used to demonstrate the origin of action. It is often translated in english with the word "from". Nevertheless, it can have other uses. Ablative case is also used in many other languages : armenian, azerbaijani, latin, german, albanian, greek, finnish, hungarian, sanskrit, nepali and many others.
In mongolian language, ablative is created by adding the suffix –аас, -өөс, -оос, -ээс to the basic morpheme (word). The addition of the suffix of the ablative, as in all other cases, is inevitably linked the principle of vocal harmony. That is to say that the vowel of the suffix must be of the same class (anterior or posterior) as the vowels found in the primary radical. In other word, Канад will become Канадаас and Орос will become "Оросоос"
In the same way, Монгол "Mongolia" becomes Монголоос "from Mongolia". Words ending in a double vowel will have an -н- added: хөдөө "the countryside" becomes “хөдөөнөөс" from the countryside". According to the letters preceedings, one can also see the addition of a -г-.
Канад → Canada → Канадаас ...from Canada
Хөдөө → countryside → Хөдөөнөөс ...from the countryside
Хот → city → Хотоос ...from the city
Улаанбаатар → Ulan-Bator → Улаанбаатараас ...from Ulan-Bator
Гэр → yurt → Гэрээс ...from the yurt
Хаана → where → Хаанаас ...from where
Cургууль → school → Cургуулиаc ...from the school
Хороoлол → neighborhood → Хороoлoлooc ...from the neighborhood
Франц → France → Францаас ...from France
Монгол → Mongolia → Монголоос ...from Mongolia
Өчигдөр → yesterday → Өчигдрөөс ...from/since yesterday
Их сургууль → University → Их сургуулиаc → ...from the university
Цайны газар → Cantine → Цайны газрaaс → ...from the canteen
Зочид буудал → Hotel → Зочид буудлаас → ...from the hotel
When two or more words must put in a particular case, only the last take the mark of the corresponding case:
a) Би энэ номыг ааваасaa авсан. → I took this book from my father
b) Өчигдөр ах хөдөөнөөс ирсэн. →Yesterday, my brother came from the countryside.
c) Аав хоёр гурав хоногоос ирнэ. →Father will come in 2-3 days (from 2-3 days).
d) Oюутан өчигдөр Монголоос ирэв. → The student came yesterday from Mongolia.
e) Тэр судлаач өглөөнөөс хойш хүлээсэн. → This scientist is waiting in the morning.
f) Oюутан багшаас залуу. → The student is younger than the teacher (from the teacher).
g) Улаанбаатар Moсквагаас жижиг. → Ulan-Bator is smaller than Moscow.
h) Би энэ толь бичиг дэлгүүрээс авсан. → I bought this dictionary from the shop.