Baal Shem in Hebrew translates as "Master of the Name", and is almost always used in reference to Israel ben Eliezer, the Rabbi who founded Hasidic Judaism and was called the Baal Shem Tov, or Master of the Good Name.

More general, it refers to a rabbi who, due to his ability to perform super- and supra-good deeds that benefit others, is "given" the title by those who recognize or have benefited from his powers. It's a name that was given in the Middle Ages to a Jewish rabbi miracle worker who could bring about cures and healing, as well having mystical powers to foresee or interpret events and personalities. They were considered to have a "direct line" to Heaven evoking God's mercies and compassion on suffering human beings.

Not many people with this title have been recorded (outside of the Baal Shem Tov, the Baal Shem of Michelstadt was one example) and none have it today. It mainly survives in Jewish surnames of people descending from Ba'ale Shem such as Balshem, Balshemnik and Bolshemennikov.