Bosnian is
the national origin of anybody who has a Bosnian heritage and was born in
Bosnia, not mattering what religion they are(unless of course they do not see themselves as Bosnian like most catholics and
orthodox christians there, but not all).
For the record somebody from
Hercegovina is also a Bosnian because Hercegovina was never a independent region, but a region in Bosnia. It only received the name Hercegovina (after Hrzeg
Stjepan who was a warlord in the Hum region today Herzegovina)long after being a Bosnian territory. Even during the Ottoman time Herzegovina was a territory in Bosnia( a sandzak in the Bosnian Pashadom) and the name
Bosnia and Herzegovina came only to be during the creation of Yugoslavia(due to political reasons).