metasyntactic variable n. A name used in examples and understood to stand for whatever thing is under discussion, or any random member of a class of things under discussion. The word foo is the canonical example. To avoid confusion, hackers never (well, hardly ever) use `foo' or other words like it as permanent names for anything. In filenames, a common convention is that any filename beginning with a metasyntactic-variable name is a scratch file that may be deleted at any time.

To some extent, the list of one's preferred metasyntactic variables is a cultural signature. They occur both in series (used for related groups of variables or objects) and as singletons. Here are a few common signatures:

foo, bar, baz, quux, quuux, quuuux...: MIT/Stanford usage, now found everywhere (thanks largely to early versions of this lexicon!). At MIT (but not at Stanford), baz dropped out of use for a while in the 1970s and '80s. A common recent mutation of this sequence inserts qux before quux. bazola, ztesch: Stanford (from mid-'70s on). foo, bar, thud, grunt: This series was popular at CMU. Other CMU-associated variables include gorp. foo, bar, fum: This series is reported to be common at XEROX PARC. fred, barney: See the entry for fred. These tend to be Britishisms. toto, titi, tata, tutu: Standard series of metasyntactic variables among francophones. corge, grault, flarp: Popular at Rutgers University and among GOSMACS hackers. zxc, spqr, {wombat}: Cambridge University (England). shme Berkeley, GeoWorks, Ingres. Pronounced /shme/ with a short /e/. foo, bar, zot Helsinki University of Technology, Finland. blarg, wibble New Zealand

Of all these, only `foo' and `bar' are universal (and baz nearly so). The compounds foobar and `foobaz' also enjoy very wide currency.

Some jargon terms are also used as metasyntactic names; barf and mumble, for example. See also Commonwealth Hackish for discussion of numerous metasyntactic variables found in Great Britain and the Commonwealth.