In old-Croatian, this earliest geographical term appeared at least from 10th century within the Glagolitic inscriptions in Chakavian dialect, e.g. in Baška tablet about 1105, and also in some subsequent Glagolitic texts as krayna (pronouncing 'kraüna') in the original medieval meaning of inlands or mainlands. In this similar meaning it is inherited now by the native Chakavian elders of northern Dalmatian islands and Kvarner archipelago, where also the related krayane means 'inlanders'.
Then since the Turkish incursions followed by the prevailing of Shtokavian dialect, old krajina gradually shifted to its recent meaning of a county or surroundings of a certain town. In the modern Croatian of mainlands, it mostly refers to the area around certain small cities. The term is almost applied to Zagora and areas neighbouring Zagora to the west.
In some South Slavic languages especially in Serbian, the word krajina refers primarily to border or borderland of a country, with established military defense, and secondarily to a region, area, or landscape; but in medieval Croatian of Glagolitic texts the last is its primary earlier meaning and military role appeared since Turks. The word kraj can mean end or extremity, or region or area. Archaically extrapolated, it could mean "army" or "war" in Serbian, but a "mainland" or "continent" in early Glagolitic Croatian. The Serbian term is equal to German Mark and French marche, but the old-Croatian Glagolitic is subequal to the Romance Terrafirma as opposed to coast or islands.
In other Slavic languages (including Chakavian and Kajkavian dialects of the Croatian language), the term has other meanings, either territorial name (cf. Krajna in Poland) or word with meaning "a land, landscape" (e.g. in Slovak, Czech or Sorbian).
- Bosnia and Herzegovina
- Bosanska Krajina, around Banja Luka and encompassing a larger area, also on older maps called Turkish Croatia; westwards from Vrbas river, on the NW from Završje (on older maps, Završje is a part of Croazia Turca, Türkisch Kroatien, Török Horvátország )
- Cazinska Krajina, borderland of Bosnia towards Croatia around the city of Cazin.
- Krayna vu Otoce: medieval Glagolitic name of Gacka valley in Lika highlands
- Cetinska krajina, area along the valley of river Cetina in the southern Croatia, in Zagora, to the east from Herzegovina (Bosnia and Herzegovina), mostly containing Sinjsko polje
- Drniška krajina, area around the city of Drniš in southern Croatia, in Zagora, to west from Cetinska krajina
- Imotska krajina, area around the city of Imotski, in southern Croatia, in Zagora mostly containing Imotsko polje, to east from Cetinska and Omiška krajina, to west from Vrgoračka krajina; also the name of the soccer club from Imotski
- Istarska krajina, historical region in western Croatia, central area of peninsula of Istria 
- Kninska Krajina, region around Knin in southern Croatia, to north from Drniška krajina and northeast from Cetinska krajina
- Neretvanska krajina, historical area westwards from river of Neretva, southwest from župa Imota 
- Omiška krajina, region in hinterland of city of Omiš, in Croatian south, in Zagora; to east from Cetinska krajina, to west from Cetinska krajina
- municipality of Krajina, a municipality in southern Croatia, located between Split and Imotski, existed from 1912-1945 
- Sinjska krajina, area in Zagora, in southern Croatia, around the city of Sinj, west from Livanjski kraj, southeast from Vrlička krajina (sometimes considered as part of Cetinska krajina)
- Vrgoračka krajina, area in Zagora, in southern Croatia, around the city of Vrgorac, southwest from Herzegovina and west from Neretva valley, to east from Imotska krajina
- Vrlička krajina, area in Zagora, in southern Croatia, around the city of Vrlika, west from Livanjski kraj, northwest from Cetinska krajina (sometimes considered as part of Cetinska krajina)
- Krajina is also a Croat surname
- a part of peri-littoral area near Makarska in Croatia is called Krajina (see reference)
Subdivisions of Austria-Hungary:
- Military Krajina (Military Frontier, Militärgrenze), borderland of Austria against the Ottoman Empire. It was further divided into:
Political units formed during the war in Croatia in the 1990s:
- Republic of Serbian Krajina
- SAO Krajina
- SAO Kninska Krajina, Kninska Krajina since the Yugoslav wars is used by some to signify two regions Knin and its surroundings, and to a larger extend Krajina proper (referring to main portion of Republic of Serb Krajina).
- SAO Eastern Slavonia, Baranja and Western Srem, sometimes called Podunavska Krajina
Political unit formed during the war in Bosnia and Herzegovina in the 1990s:
Where the term "Serbian Krajina" or "Krajina" alone is used, it probably refers to the former Republic of Serbian Krajina.
- "krai" or "kray" is the word for the territories of Russia, a second-level subdivision
- "kraj" is used for the regions of Slovakia, a first-level subdivision
In Czech Republic:
- "kraj" is used for the regions of the Czech Republic, a first-level subdivision
- Krajina or країна - means country, land in Ukrainian. Ukrajina is Ukrainian ethnonym for Ukraine. See also: Name of Ukraine.
- Group of authors (1969). "Кра̏јина". Речник српскохрватскога књижевног језика, vol. 3 (in Serbo-Croatian). Novi Sad/Zagreb: Matica srpska/Matica hrvatska. p. 30.
- Group of authors (1972). "Krajina". In colonel-general Nikola Gažević. Vojna enciklopedija, vol. 4 (in Serbian). Belgrade. p. 681.
- Pándi Lajos - Köztes Európa 1756-1997
- Croatia in 1073
- (Croatian) Excerpt from the book I. Marinović, B. Šutić, M. Viskić: Baćina: Prošlost Baćine, Udruga Pagania, Ploče, 2005, ISBN 953-95132-0-0
- (Croatian) Povijest
- Karlo Jurišić, Lepantska pobjeda i makarska Krajina, Adriatica maritima, sv. I, (Lepantska bitka, Udio hrvatskih pomoraca u Lepantskoj bitki 1571. godine), Institut JAZU u Zadru, Zadar, 1974., str. 217., 222., (reference from Morsko prase)