obelus

The name of the symbol "

", used as a sign for division. It comes from the Greek obelos meaning a pointed stick – a spit – used for cooking. This root word also gave rise to "obelisk" for a pointed stone pillar of stone. The "

" symbol was originally used as an editing mark in early manuscripts, sometimes only as a line without the two dots, to point out material that the editor thought needed cutting. It was also used occasionally as a symbol for subtraction. As a division symbol it was first employed by the Swiss mathematician Johann Rahn (1622–1676) in his Teutsche Algebra in 1659. By a misunderstanding of a credit to John Pell about other material in the book, many English writers started using the symbol and calling it Pell's notation. Although it appears regularly in literature produced in Britain and the United States, it is virtually unknown in the rest of the world.

Related category

• SYMBOLS AND NOTATION

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