Skorowidz Miejscowości Rzeczypospolitej Polskiej [Index of Placenames of the Republic of Poland] circa 1931.
A gazetteer is a geographical dictionary or directory, an important reference for information about places and place names (see: toponymy), used in conjunction with a map or a full atlas. It typically contains information concerning the geographical makeup of a country, region, or continent as well as the social statistics and physical features [source: Wikipedia]. The features genealogists look for are: administrative levels (state/woj., county/pow., township/gmina) or location of parishes/parafialny. So the “Skorowidz” gives us this info, if we can know the name of the place/village we are looking up info upon.
I have created a mini index of this Gazetteer age paging through 2096 pages sequentially or randomly is not very productive. My index page for Skorowidz Miejscowości Rzeczypospolitej Polskiej is here. So I wish you good research in locating your ancestral village and its parish/synagogue. One final note! There are many excellent Gazetteers for Poland, but that will be another article.