Wide boy is a British term for a man who lives by his wits, wheeling and dealing. According to the Oxford English Dictionary it is synonymous with spiv. The word "wide" used in this sense means wide-awake or sharp-witted. It applies to the wide-lapelled suits and broad ties, commonly called ' Kipper's ', after the similarly broad fish, which were worn. The term was used in a 1936 autobiography to describe criminal culture during the First World War. Newspapers of the late 1940s and 1950s often use both terms in the same article about the same person when dealing with ticket touts, fraudsters, and black market traders. It has become more generally used to describe a dishonest trader or a petty criminal who works by guile rather than force.

An early use of the term was in the 1933 film "Friday the Thirteenth", where the character, played by Max Miller, a loud, quick-witted, Cockney market trader, is heard to say "I'm the widest boy ever put on a pair of shoes!"

The term came to public attention in 1937 with the publication of Wide Boys Never Work by Robert Westerby, a novel about gamblers and hustlers. During World War II such individuals became involved in the black market, but the term only began to appear in newspapers from 1947.