Lomna may refer to:
- Lomná, Námestovo, a village in the Žilina Region of Slovakia
- Lomná (river) (also known as Lomňanka), a tributary of the Olza River, Czech Republic
- Dolní Lomná, a village in the Moravian-Silesian Region of the Czech Republic
- Horní Lomná, a village in the Moravian-Silesian Region of the Czech Republic
- Łomna, Lesser Poland Voivodeship, a village in southern Poland
- Łomna, Nowy Dwór Mazowiecki County, a village in Masovian Voivodeship, Poland
- Łomna, Sokołów County, a village in Masovian Voivodeship, Poland
- Łomna, Subcarpathian Voivodeship, a village in south-eastern Poland
( Polish: , Cieszyn Silesian: ) also known as ( Polish: , Cieszyn Silesian: ) is a -long river in Frýdek-Místek District, Moravian-Silesian Region, Czech Republic, in the historical region of Cieszyn Silesia.
It is the left tributary of the Olza River, to which it enters in Jablunkov (Jabłonków). It originates near the border with Slovakia and flows through the villages of Horní Lomná (Łomna Górna), Dolní Lomná (Łomna Dolna) and Bocanovice (Boconowice).
It was mentioned in 1592 as przi rzece Lomny. The name is derived from the words łom (clatter, rumble, susurrus) or załom (turn, bend).
Image:Lomna 639.jpg|Lomná in Dolní Lomná Image:Lomna 032.jpg|Lomná in Dolní Lomná