ὀβελός

Etymology
Possibly an alteration of, but the initial vocal cannot be accounted for. According to Beekes and Furnée, the word is clearly.

Noun

 * 1) a spit, rod
 * 2)  a pointed square pillar, obelisk
 * 3) a horizontal line
 * 1)  a pointed square pillar, obelisk
 * 2) a horizontal line

Usage notes
The horizontal line was used as a critical mark to point out that a passage was spurious, but with one point below and one above (÷) it denoted superfluous passages, especially in philosophical writings.