Barber was originally named Manassas. Manassas is a form of the Hebrew name for Manasseh which means "making forgetfulness". Perhaps something is lost in the translation. It is not known how old Manassas is, it may predate Trappe. It is said that the name was changed to Barber after Isaac Barber a politician and physician who owned land nearby when it got a post office in 1898. The post office lasted only 5 years, but Barber it remains.
To complicate things, the name is shown here as Hughlett and as having a post office. The Hughlett's had a shipyard at Jamaica Pt. just south of Barber, so perhaps that is where that name came from. Perhaps Manassas became a convenient settlement for shipyard laborers which might explain the change of name.
Postal records show that Hughlett only had a post office for a few months in 1882, so this map is somewhat out of date. It is possible that Manassas/Hughlett regained its post office through the efforts of Isaac Barber in 1898 hence the new name, but that is speculation.