The word "pabaiskas" is derived from Polish "pobojowisko" literally meaning "battle site". Its alternate names include Pabaisko, Pabayskas, Pobojsk (Polish), and Paboisk (Yiddish).
There is a Holy Trinity Church in the town, built in 1436 by Sigismund Kestutaitis. A more modern stonework church was built in 1821–1836 m. The architect was J. Levoisier.