Adopted in the 17th century, from Russian Сибирь (Sibirʹ). In origin the Tatar name of a 14th-century fortress at Qashliq (Tobolsk) which became the capital of the 16th-century Khanate of Sibir, in 16th century Russian usage extended to the entire area of what is now Tyumen Oblast, and with the ongoing Russian conquest of Siberia by the 19th century to the larger area of Russia's Asian territories beyond the Ob River.
The figurative sense in English arises in the 19th century (attested in 1841 according to OED).
- (figuratively) a cold, inhospitable place or place of exile
First declension with locative.