RFC 3092 - Etymology of "Foo"

Approximately 212 RFCs, or about 7% of all RFCs issued so far, contain the terms foo, bar, or foobar as metasyntactic variables without any proper explanation or definition. This document rectifies that deficiency.

Definition and Etymology

The RFC provides the following definitions:

• bar /bar/ n. [JARGON] 1. The second metasyntactic variable, after foo and before baz. "Suppose we have two functions: FOO and BAR. FOO calls BAR...." 2. Often appended to foo to produce foobar.
• foo /foo/ 1. interj. Term of disgust. 2. Used very generally as a sample name for absolutely anything, esp. programs and files (esp. scratch files). 3. First on the standard list of metasyntactic variables used in syntax examples (bar, baz, qux, qux, corge, grault, garply, waldo, fred, plugh, xyzzy, thud).

Historical Origins

The etymology traces back to several sources:

1. WWII Military Slang: The term is generally traced to the WWII era Army slang acronym FUBAR (Fucked Up Beyond All Repair), later modified to foobar. Early versions of the Jargon File interpreted this change as a post-war bowdlerization, but it now seems more likely that FUBAR was itself a derivative of foo perhaps influenced by German furchtbar (terrible).

2. Comic Strips and Cartoons: The word foo itself had an immediate prewar history. In the 1938 Warner Brothers cartoon "The Daffy Doc", a very early version of Daffy Duck holds up a sign saying "SILENCE IS FOO!" FOO and BAR also occurred in Walt Kelly's "Pogo" strips.

3. Smokey Stover: The earliest documented uses were in the surrealist "Smokey Stover" comic strip by Bill Holman about a fireman. This comic strip appeared in various American comics including "Everybody's" between about 1930 and 1952. It frequently included the word "FOO" on license plates of cars, in nonsense sayings in the background such as "He who foos last foos best" or "Many smoke but foo men chew", and had Smokey say "Where there's foo, there's fire".

Bill Holman claimed to have found the word "foo" on the bottom of a Chinese figurine. This is plausible; Chinese statuettes often have apotropaic inscriptions, and this may have been the Chinese word fu (sometimes transliterated foo), which can mean "happiness" when spoken with the proper tone.

Military Usage

During WWII, the term foo fighters was in use by radar operators for the kind of mysterious or spurious trace that would later be called a UFO. Informants connected the term to the Smokey Stover strip. The U.S. and British militaries frequently swapped slang terms during the war. Period sources reported that FOO became a semi-legendary subject of WWII British-army graffiti more or less equivalent to the American Kilroy. Where British troops went, the graffito "FOO was here" or something similar showed up.

MIT Connection

In 1959, the Tech Model Railroad Club at MIT had an entry for Foo in their dictionary: "The sacred syllable (FOO MANI PADME HUM); to be spoken only when under obligation to commune with the Deity. Our first obligation is to keep the Foo Counters turning."

Acronyms

The RFC also documents various acronyms using these terms:

• BAR: Base Address Register, Buffer Address Register
• FOO: Forward Observation Observer, File Open for Output (an NFILE error code)
• FOOBAR: FTP Operation Over Big Address Records
• FUBAR: Failed UniBus Address Register, Fucked Up Beyond All Recognition/Repair

RFC Occurrences

The RFC includes an appendix documenting RFC occurrences of these words as metasyntactic variables. As of RFC 3092, there were 212 RFCs containing these terms, with usage patterns showing:

• foo appears in 212 RFCs
• bar appears in 150 RFCs
• foo.bar appears in 50 RFCs
• fubar appears in 30 RFCs
• foobar appears in 25 RFCs

Security Considerations

Security issues are not discussed in this memo.

References

The RFC cites numerous sources including:

• The Jargon File
• RFC 269 (the first RFC to use "foo")
• Various comic strip references
• Military slang dictionaries
• Personal communications

Authors' Addresses

The authors are Donald E. Eastlake 3rd (Motorola), Carl-Uno Manros (Xerox Corporation), and Eric S. Raymond (Open Source Initiative).

This April 1st RFC serves both as a genuine etymological reference and as a humorous acknowledgment of a long-standing gap in Internet documentation. While published as an Informational RFC, it has become a definitive reference for understanding these ubiquitous metasyntactic variables that appear throughout technical documentation and programming examples.