foo

From Mandarin 府 (fǔ).

From Chinese 福 (fú, “fortunate; prosperity, good luck”), via its use as 福星 (Fúxīng, “Jupiter”) in Chinese statues of the Three Lucky Stars, picked up from c. 1935 as a nonsense word in Bill Holman's Smokey Stover comic strip, whence it was picked up by Pogo, Looney Tunes, and others. Used by Jack Speer as the name of a mock god of mimeography in the 1930s.

Popularized in computing contexts by the Tech Model Railroad Club's 1959 Dictionary of the TMRC Language, which incorporated it into a parody of the Buddhist chant

A minced form of fuck.