Metasyntactic Variable


A metasyntactic variable is often used in computer programming as a placeholder name for an unspecified entity. It’s used when the actual object doesn’t matter for the purpose of the explanation or example. Common metasyntactic variables include “foo”, “bar”, “baz”, and so on.


The phonetic spelling of “Metasyntactic Variable” is:mɛtəˌsɪntækˈtɪk ˈvɛərɪəbəl

Key Takeaways

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  1. Metasyntactic Variable: A term used in computer science to denote placeholder names or temporary variables in source code, scripts, or command lines. Common examples include ‘foo’, ‘bar’, and ‘baz’.
  2. Purpose: These are predominantly used for documentation and teaching, where the specific identity of a variable doesn’t matter much. Metasyntactic variables are parts of the program that a programmer expects to modify for a particular installation or execution.
  3. Origin and Usage: The terms ‘foo’ and ‘bar’ which are popularly used as metasyntactic variables have their origins in military slang ‘FUBAR’. It’s also a standard catchphrase among programmers when creating examples or when the names of the variables they are used don’t play any role.



The term “Metasyntactic Variable” is important in technology, particularly in the realm of programming, because it’s used to refer to unspecified variables or items that are being discussed or demonstrated. They act as placeholder names in computer programming, often used when the actual names or values are not significant. “Foo” and “Bar” are the most common examples of metasyntactic variables. They aid programmers in illustrating concepts, writing example codes, and designing algorithms without emphasizing the actual variable name. Therefore, metasyntactic variables serve as an essential tool in explaining, understanding, and testing abstract programming concepts.


A metasyntactic variable serves an essential role in computer programming and linguistics, typically employed to signify or stand in for an undefined entity, concept, or term that is subject to change. It’s largely utilized in the same capacity as a placeholder would be, such as a variable form or function name that carries no inherent meaning of its own. The usage of metasyntactic variables shines when examples or code snippets are presented as they are used to replace context-specific names with ones that clearly indicate their placeholder status. For this reason, they’re often found in tutorial examples and theoretical discussions regarding the syntax or semantic rules of a computer language.The practice of employing metasyntactic variables is hugely beneficial for making programming code more easily comprehensible. Remember, the purpose of a metasyntactic variable is not to be descriptive of function or value, but instead to unmistakably signal that it is a replaceable placeholder. This reduces the distraction of unnecessary details, allowing for more focus on the structure and logic flow of code in discussion or learning. Moreover, the use of such variables can help in avoiding potential confusion for beginners or non-expert programmers by not introducing application-specific terminology unnecessarily.


A metasyntactic variable is a placeholder name or alias used in computer science to stand for an unspecified entity, such as an function, variable, or data type. Here are three real-world examples:1. “Foo” and “Bar”: Probably the most widely used metasyntactic variables in coding, foo and bar are used in countless programming and documentation examples. If there was a program that needed two variables but the actual names of the variables were not important to the functionality of the program, a programmer might use foo and bar as placeholders.2. “Lorem Ipsum”: In web design and typesetting, metasyntactic variables are used as dummy text. “Lorem ipsum” is a section of a Latin text by Cicero used as placeholder, filler or to demonstrate the graphic elements of a document or visual presentation.3. “X” and “Y”: In mathematics or related fields like data analysis, X and Y are often used as metasyntactic variables. For example, in a scatterplot, one might not yet know what the X and Y axis will represent, so X and Y are used as placeholders until the specific data is determined.

Frequently Asked Questions(FAQ)

Q: What is a Metasyntactic Variable?A: A Metasyntactic Variable is a placeholder name commonly used in computer science to refer to unknown or unspecified variables. Examples are ‘foo’ and ‘bar’ in English, or ‘blabla’ in French.Q: What are common examples of Metasyntactic Variables?A: Some of the most common Metasyntactic Variables used in computer science are “foo”, “bar”, “baz”, “qux”, “quux”, “corge”, “grault”, “garply”, “waldo”, “fred”, “plugh”, “xyzzy”, and “thud”.Q: Where are Metasyntactic Variables used?A: They are often used in computer programming, documentation, and instruction, typically to demonstrate a concept, code function, or algorithm.Q: Who coined the term ‘Metasyntactic Variable’?A: The term ‘Metasyntactic Variable’ was popularized by the Jargon File, a glossary of computer programmer slang.Q: Why are Metasyntactic Variables used instead of specific names?A: Metasyntactic Variables are used to avoid confusion with other parts of the code and to signal the nonspecific nature of the variable, making it clear that the same code can be applied to other data.Q: Are Metasyntactic Variables only used in English?A: No, each programming language community may use its own Metasyntactic Variables. For example, in French, commonly used Metasyntactic Variables are ‘toto’, ‘titi’, ‘tata’, ‘tutu’.Q: Can I use any name for a Metasyntactic Variable?A: Yes, in theory you could use any name. However, using common ones like ‘foo’ and ‘bar’ makes your code easier for others to understand.

Related Tech Terms

  • Foobar
  • Placeholder Name
  • Syntax
  • Dummy Variable
  • Programming Language Semantics

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