Jacnia [ˈjat͡sɲa] is a village in the administrative district of Gmina Adamów, within Zamość County, Lublin Voivodeship, in eastern Poland. It lies approximately 3 kilometres (2 mi) south-east of Adamów, 18 km (11 mi) south of Zamość, and 86 km (53 mi) south-east of the regional capital Lublin.