Indonesian as a modern dialect of Malay has borrowed heavily from many languages, among others: Sanskrit, Arabic, Portuguese, Dutch, Chinese and many other languages, including other Austronesian languages. It is estimated that there are some 750 Sanskrit loanwords in modern Indonesian, 1000 Arabic (Persian and some Hebrew) ones, some 125 Portuguese (also Spanish and Italian) ones and a staggering number of some 10,000 loanwords from Dutch. The latter also comprises many words from other European languages, which came via Dutch, the so-called "International Vocabulary". The vast majority of Indonesian words, however, come from the root lexical stock of its Austronesian heritage.
Although Hinduism and Buddhism are no longer the major religions of Indonesia, Sanskrit which was the language vehicle for these religions, is (still) held in high esteem and is comparable with the status of Latin in English and other West European languages. Residents of Bali and Java tend to be particularly proud of the Hindu-Buddhist heritage. Sanskrit is also the main source for neologisms. These are usually formed from Sanskrit roots. The loanwords from Sanskrit cover many aspects of religion, art and everyday lives. The Sanskrit influence came from contacts with India long ago from the beginning of the Common Era. The words are either directly borrowed from India or with the intermediary of the (Old) Javanese language. In the classical language of Java, Old Javanese, the number of Sanskrit loanwords is far greater. The Old Javanese - English dictionary by prof. P.J. Zoetmulder, S.J. (1982) contains no fewer than 25,500 entries. Almost half are Sanskrit loanwords. Unlike other loanwords, Sanskrit loanwords have entered the basic vocabulary of Indonesian, so by many these aren't felt as foreign anymore.
The loanwords from Arabic are mainly concerned with religion, in particular with Islam, as can be expected. Many early Bible translators, when they came across some unusual Hebrew words or proper names, used the Arabic cognates. In the newer translations this practice is discontinued. They now turn to Greek names or use the original Hebrew Word. For example, the name Jesus was initially translated as 'Isa, but is now spelt as Yesus. Psalms used to be translated as Zabur, the Arabic name, but now it is called Mazmur which corresponds more with Hebrew.
The Portuguese loans are common words, which were mainly, connected with articles the early European traders and explorers brought to Southeast Asia. The Portuguese were among the first westerners who sailed east to the "Spice Islands".
The Chinese loanwords are usually concerned with cuisine, trade or often just exclusively things Chinese. There is a considerable Chinese presence in the whole of Southeast Asia. According to the Indonesian government, the relative number of people of Chinese descent in Indonesia is only 3.5%. Whether this is true or not is still a matter of debate, many think the number is much higher. But what is sure is that in urban centres the number can be as high as between 10-25%.
The former colonial power, the Netherlands, left an impressive vocabulary. These Dutch loanwords, and also from other non Italo-Iberian, European languages loanwords which came via Dutch, cover all aspects of life. Some Dutch loanwords, having clusters of several consonants, pose difficulties to speakers of Indonesian. This problem is usually solved by insertion of the schwa. For example Dutch schroef ['sxruf] => sekrup [se'krup].
As modern Indonesian draws many of its words from foreign sources, there are many synonyms. For example, Indonesian has three words for book, i.e. pustaka (from Sanskrit), kitab (from Arabic) and buku (from Dutch). These words have, as can be expected, slight different meanings. A pustaka is often connected with ancient wisdom or sometimes with esoteric knowledge. A derived form, perpustakaan means a library. A kitab is usually a religious scripture or a book containing moral guidances. The Indonesian word for the Bible is Alkitab, thus directly derived from Arabic. The book containing the penal code is also called the kitab. Buku is the most common word for books.
In addition to those above, there are also direct borrowings from various languages in the world, such as "karaoke" from Japanese, and "modem" from English.