Reb (Yiddish: רב, /ˈrɛb/) is a Yiddish or Hebrew honorific traditionally used for Orthodox Jewish men. It is not a rabbinic title.[1] In writing it is abbreviated as ר׳. On a gravestone, ב'ר is an abbreviation for ben/bat reb meaning "son/daughter of the worthy..."[1] Reb may also be a short form of Rebbe. It is generally only used for married men, sometimes an equivalent of "Mr."
The title was adopted by Jews at the time of the schism with the Karaites, as a sign of loyalty to Rabbinic Judaism.[5]
When addressing someone directly, Reb is usually used with the first name only ("May I help you, Reb Chaim?"). In other circumstances, it can be used with either the first name or the full name ("This is Reb Chaim Jacobs."; "Would you please help Reb Chaim?"). In formal written address, it is usually used along with the full name.