Definition of "foo" in English

noun

1. (historical, obsolete) Alternative form of fu: an administrative subdivision of imperial China; the capital of such divisions.

noun

1. (programming) A metasyntactic variable used to represent an unspecified entity. If part of a series of such entities, it is often the first in the series, and followed immediately by bar.

   • Suppose we have two objects, foo and bar.

2. (fandom slang) Alternative letter-case form of Foo (“placeholder god”).

interjection

1. Expression of disappointment or disgust.

   • Oh foo – the cake burnt!

noun

1. (slang) Pronunciation spelling of fool.