Dialects of Serbo-Croatian
Kajkavian is spoken in North Croatia, including the capital Zagreb, as well as in a few enclaves in Austria, Hungary, and Romania. Though its speakers are ethnic Croats and Kajkavian is thus generally considered a dialect of Serbo-Croatian, it is closer to neighboring Slovene than it is to Chakavian or Shtokavian. The Kajkavian area of Croatia is bordered on the northwest by Slovene language territory. It is bordered on the east and southeast by Shtokavian dialects roughly along a line that was the former division between Civil Croatia and the Habsburg Military Frontier; in southwest along Kupa and Dobra rivers, it persisted in ancient (medieval) contact with Chakavian dialects.
Bosnian language
Bosnian is based on the most widespread dialect of Serbo-Croatian, Shtokavian, more specifically on Eastern Herzegovinian, which is also the basis of Standard Croatian, Serbian, and Montenegrin. Until the dissolution of SFR Yugoslavia, they were treated as a unitary Serbo-Croatian language, and that term is still used in English to subsume the common base (vocabulary, grammar and syntax) of what are today officially four national standards, although this term is controversial for native speakers, and paraphrases such as "Serbo-Croato-Bosnian" (SCB) or "Bosnian-Croatian-Serbian" (BCS) are therefore sometimes used instead, especially in diplomatic circles.