Serbo-Croatian:

Throughout the history of the South Slavs, the vernacular, literary, and written languages (e.g. Chakavian, Kajkavian, Shtokavian) of the various regions and ethnicities developed and diverged independently. Prior to the 19th century, they were collectively called "Illyric", "Slavic", "Slavonian", "Bosnian", "Dalmatian", "Serbian" or "Croatian". As such, the term Serbo-Croatian was first used by Jacob Grimm in 1824, popularized by the Vienna philologist Jernej Kopitar in the following decades, and accepted by Croatian Zagreb grammarians in 1854 and 1859. At that time, Serb and Croat lands were still part of the Ottoman and Austrian Empires. Officially, the language was called variously Serbo-Croat, Croato-Serbian, Serbian and Croatian, Croatian and Serbian, Serbian or Croatian, Croatian or Serbian. Unofficially, Serbs and Croats typically called the language "Serbian" or "Croatian", respectively, without implying a distinction between the two, and again in independent Bosnia and Herzegovina, "Bosnian", "Croatian", and "Serbian" were considered to be three names of a single official language. Croatian linguist Dalibor Brozović advocated the term Serbo-Croatian as late as 1988, claiming that in an analogy with Indo-European, Serbo-Croatian does not only name the two components of the same language, but simply charts the limits of the region in which it is spoken and includes everything between the limits (‘Bosnian’ and ‘Montenegrin’). Today, use of the term "Serbo-Croatian" is controversial due to the prejudice that nation and language must match. It is still used for lack of a succinct alternative, though alternative names have been used, such as Bosnian/Croatian/Serbian (BCS), which is often seen in political contexts such as the Hague War Crimes tribunal.

Please answer a question about this article. If the question is unanswerable, say "unanswerable". What was the language unofficialy known as according to the Ottoman emprire?
unanswerable