Hipster or hepcat, as used in the 1940s, referred to aficionados of jazz, in particular bebop, which became popular in the early 1940s. The hipster adopted the lifestyle of the jazz musician, including some or all of the following: dress, slang, use of cannabis and other drugs, relaxed attitude, sarcastic humor, self-imposed poverty and relaxed sexual codes.
The words hep and hip are of uncertain origin, with numerous competing theories being proposed. In the early days of jazz, musicians were using the hep variant to describe anybody who was "in the know" about an emerging culture, mostly black, which revolved around jazz. They and their fans were known as hepcats. By the late 1930s, with the rise of swing, hip rose in popularity among jazz musicians, to replace hep. Clarinetist Artie Shaw described singer Bing Crosby as "the first hip white person born in the United States."
In 1939, the word hepster was used by Cab Calloway in the title of his Hepster's Dictionary, which defines hep cat as "a guy who knows all the answers, understands jive". In 1944, pianist Harry Gibson modified this to hipster in his short glossary "For Characters Who Don't Dig Jive Talk", published in 1944 with the album Boogie Woogie In Blue, featuring the self-titled hit "Handsome Harry the Hipster". The entry for hipsters defined them as "characters who like hot jazz."
Hipsters were more interested in bebop and "hot" jazz than they were in swing, which by the late 1940s was becoming old-fashioned and watered down by "squares" like Lawrence Welk, Guy Lombardo and Robert Coates. In the 1940s, white youth began to frequent African-American communities for their music and dance. These first youths diverged from the mainstream due to their new philosophies of racial diversity and their exploratory sexual nature and drug habits. The drug of choice was marijuana, many hipster slang terms were dedicated to the substance.