from The American Heritage® Dictionary of the English Language, 5th Edition.
- noun A mark (— or ÷) used in ancient manuscripts to indicate a doubtful or spurious passage.
from The Century Dictionary.
- noun A mark, so called from its resemblance to a spit, usually made like a dash, thus —, or like an obelisk, thus , and employed in ancient manuscripts to indicate a suspected passage or reading.
from the GNU version of the Collaborative International Dictionary of English.
- noun (Print.) A mark [thus —, or ÷]; -- so called as resembling a needle. In old MSS. or editions of the classics, it marks suspected passages or readings.
from Wiktionary, Creative Commons Attribution/Share-Alike License.
- noun A mark (÷) used to represent
divisionin mathematics. Also used to indicate a written or printed passage, and in ancient manuscripts to mark a word or passage as spurious or doubtful.
- noun A
daggermark (†) used as a reference mark in printed matter, or to indicate that a person is deceased, often used to indicate a footnote.
from The American Heritage® Dictionary of the English Language, 4th Edition
Andrians and Corinthians, and the decree for the mutilation of the captives, of which Philokles was the author.] [Footnote 149: Golden crowns, at this period of Greek history, was the name applied to large sums of money voted by cities to men whose favour they hoped to gain.] [Footnote 150: A spit is called obelus in Greek.] [Footnote 151: Probably of each of the Spartan admirals who had commanded during the war.
_ -- What is the origin of the asterisk, obelus, &c., used for references to notes?
In the Latin text, the start and end of passages which are deeply corrupt and therefore difficult to correct are indicated by an asterisk, instead of the usual dagger (obelus).
Hexapla, the obelus was prefixed to words or lines which were wanting in the Hebrew, and therefore, from Origen's point of view, of doubtful authority, while the asterisk called attention to words or lines wanting in the Septuagint, but present in the Hebrew.
But such was not the usage of Budaeus; he employed the obelus merely to call attention to something that interested him.
The simple obelus apparently denotes interest, the pointed obelus great interest, the doubly pointed obelus intense interest, and the pointing finger of a carefully drawn hand burning interest.
The purpose of the doubly pointed obelus is plainly indicated here, as it accompanies two of these catchwords.
It is remarkable, for instance, that on a passage (65, 11) which, as the appended obelus shows, he must have read with attention, he has not added the very different reading of the Parisinus.
In accurate copies these words are marked with an obelus,  which is the sign of rejection.
Strabo xi. 507, et sq.  The obelus (/-) is used by Jerome to mark superfluous matter in the lxx.cf. Jer.p. 494, in Canon Fremantle's Translation.