Triple bar

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This article is about the symbol. For the horse jump, see oxer.
Identical to
Not identical to
apostrophe   '
brackets [ ]  ( )  { }  ⟨ ⟩
colon :
comma ,  ،  
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exclamation mark !
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semicolon ;
slash, stroke, solidus /  
Word dividers
interpunct ·
General typography
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asterisk *
at sign @
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degree °
ditto mark
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ordinal indicator º ª
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Intellectual property
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sound-recording copyright
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Uncommon typography
index, fist
irony punctuation
reference mark
In other scripts

The triple bar, , is a symbol with multiple, context-dependent meanings. It has the appearance of a "=" sign with a third line. The triple bar character in Unicode is codepoint U+2261 identical to (HTML: ≡ ≡). LaTeX \equiv corresponds to the triple bar.

In logic, it has a similar meaning to the if and only if connective, ⇔. However, in some texts ⇔ is used as a symbol in logic formulas, while ≡ is for reasoning about those formulas (as in metalogic).

In mathematics, it is sometimes used a symbol for congruence (although not the only one). Particularly, in number theory, it has the meaning of modular congruence: a \equiv b \pmod N if N divides ab.

This symbol is also used when it appears in an equation which is a definition of its left-hand side, that is an equation which is not derived but instead defined.

It is also used for "identical equality" of functions; one writes f \equiv g for two functions f, g if we have f(x) = g(x) for all x.

In botanical nomenclature, the triple bar denotes homotypic synonyms (those based on the same type specimen), to distinguish them from heterotypic synonyms (those based on different type specimens), which are marked with an equals sign.[1]

In chemistry, the triple bar can be used to represent a triple bond between atoms. For example, HC≡CH is a common shorthand for acetylene.

In website and software application design, a similar symbol is sometimes used as an interface element. The element typically indicates that a navigation menu can be accessed when the element is activated. Usage of this symbol dates back to the early computer interfaces developed at Xerox PARC in the 1980s.[2]


  1. ^ "Guidelines for authors" (PDF). Taxon 62 (1): 211–214. 2013. 
  2. ^ Cox, Norm. "The origin of the hamburger icon". Evernote.