Tech & Science dictionary foo What does foo mean? Foo is an intentionally meaningless placeholder word often used in computer programming. Where does foo come from? Examples of foo “Create an evil programming language where 'foo' and 'bar' are keywords.” Jeremy Stephens @kindlyviking Twitter (March 22, 2017) “Just realized I listen to the Foo Fighters a lot while programming because of foo bar.” @ThomKrillis Twitter (October 26, 2016) “In this example, foo(Y) is matched against Y, which appears within it.” William Clocksin and Christopher S. Mellish, Programming in Prolog (Fifth Edition) (2003) SEE MORE EXAMPLES Who uses foo? Foobar is not equivalent to the WWII military term FUBAR, an acronym for “Fucked Up Beyond All Recognition.” Though it’s possible that the linking of foo and bar might have grown out of familiarity with and playful allusion to FUBAR, programmers using foobar do not use it in this sense. “Foo was here” was a popular piece of graffiti drawn by Australian soldiers in WWII, and possibly even WWI, that depicts a little man poking his head and large nose over the wall à la Kilroy. While the origins of this foo are unclear, it appears to be unrelated to Holman’s foo. Foo’ is sometimes also used as a shortening of fool in English dialects, often a reference to the way the word was said by Mr. T in The A-Team. This has no connection to the programming term. Just Added Older Americans Month, Mental Health Awareness Month, Jewish American Heritage Month, Asian American and Pacific Islander Heritage Month, Saluting Face emoji Note This is not meant to be a formal definition of foo like most terms we define on Dictionary.com, but is rather an informal word summary that hopefully touches upon the key aspects of the meaning and usage of foo that will help our users expand their word mastery.