1950s; earliest use found in State of Union Year-book South Africa. From the name of Rehoboth + -er, after German Rehobother (noun) inhabitant of Rehoboth, (adjective) relating to Rehoboth, of Rehoboth, and Afrikaans Rehobother, noun. Compare earlier Rehobother Bastard, Rehoboth Bastard, Rehoboth Baster.