Janusz is a masculine given name of Polish origin and means "merciful" or "having pity". It comes from the Latin word "janua", which means "door", and was used as an honorary title in medieval Poland for those who showed mercy to prisoners, opening the "doors" of their prisons.
The name Janusz is believed to have been first used in the 15th century by the noble Polish family Januszowski. The most famous bearer of the name was Janusz Radziwiłł (1612-1658), a Polish-Lithuanian nobleman who served as the Grand Hetman of Lithuania.
Today, Janusz is still a popular name in Poland and other Slavic countries. It has also gained some international recognition due to famous bearers such as Janusz Kaminski, a Polish cinematographer known for his work with director Steven Spielberg.
The name Janusz was quite popular with 5 babies being named Janusz annually in 1994.