Slonim (Слонім; Слоним; Slanimas; Sloņima; Słonim; סלאָנים) is a city in Grodno Region, Belarus, and the administrative center of Slonim District. It is located at the junction of the Shchara and Isa rivers, southeast of Grodno. As of 2023, the population is 49,113.
Slonim has been known by several versions of its name: Сло́нім (Belarusian), Słonim (Polish), Сло́ним (Russian). Slonim was first mentioned in chronicles in 1252 as Uslonim and in 1255 as Vslonim. According to one version (which is also considered to be an official one), the name of the city originates from the Slavic word 'zaslona' (a screen), meaning that the city used to be an outpost at the southern border of Grand Duchy of Lithuania. Another version, proposed by Jazep Stabroŭski, states that Slonim is a derivative from 'Užslenimas' in the Lithuanian language simply means 'beyond the valley'.
The earliest record is of a wooden fort on the left bank of the Shchara river in the 11th century, although there may have been earlier settlement.
The area was disputed between the Grand Duchy of Lithuania and Kievan Rus' in early history and it changed hands several times. In 1040, the Kievans won control of the area after a battle but lost Slonim to the Lithuanians in 1103. The Ruthenians retook the area early in the 13th century but were expelled by a Tatar invasion in 1241 and the town was pillaged. When, later in the year, the Tatars withdrew, Slonim became part of the Grand Duchy of Lithuania once again, in personal union with the Kingdom of Poland after the Union of Krewo of 1385.
In 1532 King Sigismund I of Poland granted Slonim town rights. In 1558, King Sigismund II Augustus, in a privilege issued in Wilno, established two two-week fairs.
In 1569, the Polish–Lithuanian union was transformed into a single state and Słonim became an important regional centre within the newly established Polish–Lithuanian Commonwealth. Administratively it was part of the Nowogródek Voivodeship.