A dagger, obelisk, or obelus (†) is a typographical symbol that usually indicates a footnote if an asterisk has already been used. It is present in Unicode as U+2020†DAGGER (HTML †·†). The term "obelisk" derives from the Greek: ὀβελίσκος (obeliskos), which means "little obelus"; from ὀβελός (obelos) meaning "roasting spit". It was originally represented by the subtraction ( − ) and division ( ÷ ) symbols by Ancient Greek scholars as critical marks in manuscripts.
A double dagger or diesis (‡) is a variant with two handles that usually marks a third footnote after the asterisk and dagger. In Unicode, it is encoded as U+2021‡DOUBLE DAGGER (HTML ‡·‡).
The triple dagger (⹋) is a variant with three handles and is used by medievalists to indicate another level of notation. In Unicode, it is encoded as U+2E4B⹋TRIPLE DAGGER (HTML ⹋).
The dagger symbol originated from a variant of the obelus (plural: obeli), originally depicted by a plain line (−) or a line with one or two dots (÷). It represented an iron roasting spit, a dart, or the sharp end of a javelin, symbolizing the skewering or cutting out of dubious matter.
While the asterisk (asteriscus) was used for corrective additions, the obelus was used for corrective deletions of invalid reconstructions. It was used when non-attested words are reconstructed for the sake of argument only, implying that the author did not believe such a word or word form had ever existed. Some scholars used the obelus and various other critical symbols, in conjunction with a second symbol known as the metobelos ("end of obelus"), variously represented as two vertically arranged dots, a γ-like symbol, a mallet-like symbol, or a diagonal slash (with or without one or two dots). They indicated the end of a marked passage.
It was used much in the same way by later scholars to mark differences between various translations or versions of the Bible and other manuscripts. The early ChristianAlexandrian scholar Origen (c. 184–253 AD) used it to indicate differences between different versions of the Old Testament in his Hexapla.Epiphanius of Salamis (c. 310–320 – 403) used both a horizontal slash or hook (with or without dots) and an upright and slightly slanting dagger to represent an obelus. St. Jerome (c. 347–420) used a simple horizontal slash for an obelus, but only for passages in the Old Testament. He describes the use of the asterisk and the dagger as: "an asterisk makes a light shine, the obelisk cuts and pierces".
Isidore of Seville (c. 560–636) described the use of the symbol as follows: "The obelus is appended to words or phrases uselessly repeated, or else where the passage involves a false reading, so that, like the arrow, it lays low the superfluous and makes the errors disappear ... The obelus accompanied by points is used when we do not know whether a passage should be suppressed or not."
Medieval scribes used the symbols extensively for critical markings of manuscripts. In addition to this, the dagger was also used in notations in early Christianity, to indicate a minor intermediate pause in the chanting of Psalms, equivalent to the quaver rest notation. It also indicates a breath mark when reciting, along with the asterisk, and is thus frequently seen beside a comma.
The obelus was also occasionally used as a mathematical symbol for subtraction. It was first used as a symbol for division by the Swiss mathematician Johann Rahn in his book Teutsche Algebra in 1659. This gave rise to the modern mathematical symbol ÷.
Due to the variations as to the different uses of the different forms of obeli, there is some controversy as to which symbols can actually be considered obeli. The lemniscus (÷) and its variant, the hypolemniscus (⨪), is sometimes considered to be different from other obeli. And obeli may have referred strictly only to the horizontal slash and the dagger symbols.
The dagger usually indicates a footnote if an asterisk has already been used. A third footnote employs the double dagger. Additional footnotes are somewhat inconsistent and represented by a variety of symbols, e.g., parallels ( ‖ ), section sign ( § ), and the pilcrow ( ¶ ), some of which were nonexistent in early modern typography. Partly because of this, superscriptnumerals have increasingly been used in modern literature in the place of these symbols, especially when several footnotes are required. Some texts use asterisks and daggers alongside superscripts, using the former for per-page footnotes and the latter for endnotes.
The dagger is also used to indicate death,extinction, or obsolescence. The asterisk and the dagger, when placed beside years, indicate year of birth and year of death respectively. This usage is particularly common in German. When placed immediately before or after a person's name, the dagger indicates that the person is deceased. In this usage, it is referred to as the "death dagger". In the Oxford English Dictionary, the dagger symbol indicates an obsolete word.
In mathematics and, more often, physics, a dagger denotes the Hermitian adjoint of an operator; for example, A† denotes the adjoint of A. This notation is sometimes replaced with an asterisk, especially in mathematics. An operator is said to be Hermitian if A† = A.
In textual criticism and in some editions of works written before the invention of printing, daggers enclose text that is believed not to be original.
In chess notation, the dagger may be suffixed to a move to signify the move resulted in a check, and a double dagger denotes checkmate. This is a stylistic variation on the more common '+' (plus sign) for a check and '#' (number sign) for checkmate.
In psychological statistics the dagger indicates that a difference between two figures is not significant to a p<0.05 level, however is still considered a "trend" or worthy of note. Commonly this will be used for a p-value between 0.1 and 0.05.
In philology, the dagger indicates an obsolete form of a word or phrase.
In the early printings of the King James Bible, a dagger indicates a literal translation of a word or phrase is to be found in the margin. When used the margin begins with an abbreviation (Heb. Gk. Chald. Lat.) for the original language.
In the Geneva Bible, a double dagger indicates a literal translation of a word or phrase is to be found in the margin. When used the margin begins with an abbreviation (Heb. Gk. Chald. Lat.) for the original language.
In Anglican chant pointing, the dagger indicates a verse to be sung to the second part of the chant.
Some logicians use the dagger as an affirmation ('it is true that ...') operator.
While daggers are freely used in English-language texts, they are often avoided in other languages because of their similarity to the Christian cross. In German, for example, daggers are commonly employed only to indicate a person's death or the extinction of a word, language, species or the like.
U+2020†DAGGER (HTML †·†·Alt+0134 in Windows or option-t in macOS)
U+2021‡DOUBLE DAGGER (HTML ‡·‡·Alt+0135 in Windows or option-shift-7 in macOS)
U+2E36⸶DAGGER WITH LEFT GUARD - used in Alexander John Ellis's "palaeotype" transliteration to indicate retracted pronunciation
U+2E37⸷DAGGER WITH RIGHT GUARD - used in Alexander John Ellis's "palaeotype" transliteration to indicate advanced pronunciation
U+2E38⸸TURNED DAGGER - used in Alexander John Ellis's "palaeotype" transliteration to indicate retroflex pronunciation
U+2E4B⹋TRIPLE DAGGER - A variant with three handles.