May be you have heard it already that forming the Indonesian plural is very simple. You simply reduplicate the noun. So anak is child and anak-anak are children.
Unfortunately, this is not correct. In the Indonesian language, every noun can be either singular or plural. So mobil saya can mean both ‘my car’ as well as ‘my cars’, and saya beli pisang can mean both ‘I bought a banana’ as well as ‘I bought bananas’. Only if it is not clear from the context, you may reduplicate mobil saya to mobil-mobil saya, but as everybody understands that you bought more than one banana, there is no need to reduplicate pisang.
Reduplication also does not occur if a whole class of things is referred to such as rusa bertanduk ‘deers have antlers’. Nouns are also not reduplicated if the plurality is expressed by a number or an indefinite number (many, several etc).
Plus, there are lots of words that take a different meaning when reduplicated:
- mata ‘eye’ mata-mata ‘spy(s)’
- gula ‘sugar’ gula-gula ‘sweets’
- laki ‘husband’ laki-laki ‘man, male’
- langit ‘sky’ langit-langit ‘ceiling’
Other words only exist in their reduplicated form:
- baling-baling ‘propeller’
- paru-paru ‘lungs’
- lumba-lumba ‘dolphin’
- laba-laba ‘spider’
- kanak-kanak ‘small child, toddler’
Reduplication can be found not just in nouns but also in verbs, adjectives and other parts of speech.
So reduplication in Indonesian is not a simple matter, but actually quite complex.