Other forms: obeli; obeluses
In math, an obelus is a symbol that means "divided by," while in an ancient text it's an editorial mark on a line or word that is incorrect or doubtful.
An obelus typically looks like this: ÷, a horizontal line with dots above and below. It's familiar to anyone who's done arithmetic problems such as 12÷3=X. The original obelus conveyed "remove or cut this" in a text, with just a line symbolizing a dart or dagger. The two dots appeared later, as did a dagger-shaped version that's often added beside a person's name to mean "deceased." The word itself has a Greek root meaning "sharpened stick."