Ostrog (Russian:острог,IPA:[ɐˈstrok]) is a Russian term for a smallfort, typically wooden and often non-permanently staffed. Ostrogs were encircled by 4–6 metres highpalisade walls made from sharpened trunks. The name derives from the Russian word строгать (strogat'), "to shave the wood". Ostrogs were smaller and exclusively military forts, compared to largerkremlins that were the cores of Russian cities. Ostrogs were often built in remote areas or within the fortification lines, such as theGreat Abatis Line.
From the 17th century, after the start of theRussian conquest of Siberia, the wordostrog was used to designate the forts founded inSiberia byRussian explorers. Many of these forts later transformed into large Siberian cities.
When later Siberia became a favourite destination for criminals sent there to servekatorga, Siberian ostrogs became associated withimprisonment, and in the 18th and 19th centuries the wordostrog often meantprison.
