| Official Name: | Bač |
| Pushpin Map: | Slovenia |
| Pushpin Label Position: | top |
| Pushpin Map Caption: | Location in Slovenia |
| Subdivision Type: | Country |
| Subdivision Name: | Slovenia |
| Subdivision Type1: | Traditional region |
| Subdivision Name1: | Inner Carniola |
| Subdivision Type2: | Statistical region |
| Subdivision Name2: | Littoral–Inner Carniola |
| Subdivision Type3: | Municipality |
| Subdivision Name3: | Ilirska Bistrica |
| Area Total Km2: | 26.61 |
| Population As Of: | 2002 |
| Population Total: | 462 |
| Population Blank1 Title: | Ethnicities |
| Population Blank2 Title: | Religions |
| Coordinates: | 45.632°N 14.2574°W |
| Elevation M: | 579.7 |
| Footnotes: | [1] |
Bač (pronounced as /sl/; de|Batsch,[2] it|Baccia) is a village northeast of Knežak in the Municipality of Ilirska Bistrica in the Inner Carniola region of Slovenia.[3]
The name Bač is related to the Slovene common noun beč '(stone- or wood-lined) hollow with a spring' (< *bъťъ), referring to a local geographical feature. The Slavic word *bъťъ was borrowed from Latin buttis 'barrel' and is also the origin of the Slovene toponyms Beč and Buč.[4]
The ruins of Kalec Castle (also Na Kalcu; de|Steinberg or Stemberg)[2] [5] stand northwest of Bač near the sources of the Pivka River. The castle was built in 1620, and a cylindrical tower and walled courtyard were later added. The property was owned by the Wilicher (sl|Vilhar) family. The tower was restored in 1939, and the rest of the structure is in ruins.[5]
The local church in the settlement is dedicated to Saint Anne and belongs to the Parish of Knežak.[6]