Noun
A mark [thus /, or Ö ]; -- so called as resembling a needle. In old MSS. or editions of the classics, it marks suspected passages or readings.
Source: Webster's dictionaryThe obelus is believed to have been invented by the Homeric scholar Zenodotus as one of a system of editorial symbols. Source: Internet
St. Jerome (c. 347 – 420) used a simple horizontal slash for an obelus, but only for passages in the Old Testament. Source: Internet
The obelus accompanied by points is used when we do not know whether a passage should be suppressed or not." citation Medieval scribes used the symbols extensively for critical markings of manuscripts. Source: Internet