Obelus

An obelus is commonly used by mathematicians to signify division, but this was not the original use of either the word or the symbol; nor is it the only form that an obelus can take.

Oxford Dictionaries gives two definitions for 'obelus':

"1. A symbol (†) used as a reference mark in printed matter, or to indicate that a person is deceased.

2. A mark (− or ÷) used in ancient manuscripts to mark a word or passage as spurious, corrupt or doubtful."

Most dictionaries I've consulted on this matter (online or printed) give similar definitions to either or both of these.

Wikipedia is more expansive: 'An obelus (symbol: ÷ or †, plural: obeluses or obeli) is a symbol consisting of a short horizontal line with a dot above and another dot below, and in other uses it is a symbol resembling a small dagger. In mathematics it is mainly used to represent the mathematical operation of division. It is therefore commonly called the division sign. In editing texts an obelus takes the form of a dagger mark (†) and is used as a reference mark, or to indicate that a person is dead, and often used to indicate a footnote.

'The word "obelus" comes from ... the Ancient Greek word for a sharpened stick, spit, or pointed pillar. This is the same root as that of the word "obelisk".'

In other words: an obelus can be a minus sign or a dagger sign, as well as what we commonly call the division sign. "The minus sign" would appear to be an acceptable answer to this question – even if "equally acceptable" might be stretching the point somewhat.