The first metasyntactic variable. A generic word, not really an acronym, used as a variable name. Often found in conjunction with bar, and ultimately derived from the acronym FUBAR. For a really good feeling of what FUBAR is all about, see the movie Saving Private Ryan. In fact, see the movie anyway, but now you have something to look out for... :^)
Typical general variable name in computer science, especially liked by people who have been exposed to Lisp. Usually used with its friends, Bar and Baz. Comes from a military expression, fubar, meaning "f***ed up beyond all recognition". Related to snafu, meaning "situation normal all f***ed up". You will soon understand this...
Metasyntatic variable. A metasyntatic variable is a string that stands for or represents any syntactically appropriate string, number, or other variable. Unlike normal syntactic variables, a metasyntatic variable stands for a value of any acceptable type. For example, foo in dir foo , http://www.foo.com