The triple bar or tribar, ≡, is a symbol with multiple, context-dependent meanings indicating equivalence of two different things.
The triple bar character in Unicode is code point U+2261 ≡ IDENTICAL TO (≡, ≡).
[1] The closely related code point U+2262 ≢ NOT IDENTICAL TO (≢, ≢) is the same symbol with a slash through it, indicating the negation of its mathematical meaning.
[6] In mathematics, the triple bar is sometimes used as a symbol of identity or an equivalence relation (although not the only one; other common choices include ~ and ≈).
[13] An alternative notation for this usage is to typeset the letters "def" above an ordinary equality sign,
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.
In mobile, web, and general application design, a similar symbol is sometimes used as an interface element, where it is called a hamburger icon.
[17] Usage of this symbol dates back to the early computer interfaces developed at Xerox PARC in the 1980s.