Łęczyca [wɛnˈt͡ʂɨt͡sa] (in full The Royal Town of Łęczyca; Polish: Królewskie Miasto Łęczyca; Hebrew: לונטשיץ) is a town of 16,594 inhabitants (as of 2004) in central Poland. Situated in the Łódź Voivodeship, it is the county seat of the Łęczyca County.
The town was probably named after a Slavic tribe called Leczanie, which inhabited central Poland in the early Middle Ages. Some scholars however claim that the town was named after an Old Polish word leg or luk, which means a swampy plain.
In mediaeval Latin documents, Łęczyca is called Lonsin, Lucic, Lunciz, Lantsiza, Loncizia, Lonsitia and Lunchicia. In the early 12th century, Gallus Anonymus called Łęczyca “Lucic”, and in 1154, Arab geographer Muhammad al-Idrisi named it Nugrada, placing it among other main towns of the Kingdom of Poland, such as Kraków, Sieradz, Gniezno, Wrocław and Santok.
Łęczyca lies in the middle of the county, and has the area of 8.95 km2 (3.46 square miles). In the past, the town was the capital of the Land of Łęczyca, which was later turned into Łęczyca Voivodeship. In the Second Polish Republic and in 1945 - 1975, Łęczyca belonged to Lodz Voivodeship. In 1975-1998, it was part of Plock Voivodeship. The geometric centre of Poland is located near Łęczyca.