Definition of the word "Baju"
The word "Baju" is used in the Malaysian and Indonesian language. The direct translations for it in English are:
There are many usage for the word baju in the Malaysian language.
Baju (Dress) + Kurung (Enclosed) = Baju Kurung 
In the example above, baju kurung is the combination of two words. The literal meaning of those two words are:
1) Baju = Dress
2) Kurung = Enclosed
When you combine those two words, it becomes a single word to describe baju kurung, a type of traditional dress that can be found in Malaysia.
There are also other examples of the word "Baju"
For example, when combining two words Baju + Kebaya:
Baju (Dress) + Kebaya = Baju Kebaya 
In this example, it is used to describe another type of traditional dress that is native to Indonesia and Malaysia. Kebaya or sometimes known as baju kebaya is a noun that is used to describe a type of traditional clothing article by combining the words Baju and Kebaya.
Baju Melayu = The male version of Baju Kurung
Baju Tidur = Pyjamas
Wikipedia - Baju
Wikipedia - Baju Kurung
Wikipedia - Baju Melayu